Should I do osteotomy or cartilage grafting/implant to slim and narrow the bridge? (Photos)

Your dorsum is not the typical Asian flat one, it is very low and sunken at the radix, moderately low at the middle vault and of a normal height at the supratip; you need a perfectly matching dorsal raise graft which is thick at the radix and very thin and sharp at its lower end, so that the final assembly is a straight and canonical profile.
These Asian (Philippine, Malaysian, Thai, Chinese, Korean, etc)
ethnic noses may present different genetical issues the patients might
wish to modify, among which worth mentioning sometimes thin (Thai,
Chinese, Korean) and sometimes thick (Philippine, Malaysian) skin but
always a severe cutaneous shortfall, low dorsum, broad dorsum, flat
dorsum, broad nose, short nose, short septum, short tip, eventually
bulbous tip (not a constant feature), poorly defined tip, sometimes real
alar flare (others is a virtual or fake alar flare caused by the lack
of tip support), poorly supported tip, overrotated tip, alar rim
retraction, etc.
Its treatment is based on the principles of structure rhinoplasty
although upgraded and extended to a higher and larger level of
complexity and technical options, with massive cartilage supply from
nasal septum, ears concha and very often from rib cartilages, to restore
the enormous lack of support, the weakness and the underdevelopment of
the nasal skeleton.
Your case allows understanding the majority of anatomical features
and technical requirements of such ethnic rhinoplasties, keeping in mind
that great part of their features are common to other ethnicities like
the African, Afroamerican, Afrocaribbean, etc; the underlying skeletal
peculiarities cause the characteristic shape in this ethnicity noses and
are the reasons behind their very high surgical difficulty, which
explains why there are very few surgeons really trained, capacitated and
skilled in such ethnic rhinoplasties and why most surgeons are tempted
to employ simpler but disappointing, when not failed or even
problematic, resolution methods.
Three key aspects feature Asian noses; the barely existent dorsum and
the truncated nasal pyramid, from which half or more is missing; the
totally collapsed nasal tip which lacks any kind of support due to
totally incompetent filmy alar cartilages, tip which is also
disproportionately augmented by a huge fibrofatty pad; and sometimes the
large nostrils and excessively protruding alar flare.
The first stage after the open approach dissection of the nose is
defatting the massive pad which typically makes these noses bulbous and
large; this adipose mass is not only located above and in between the
alar cartilage domes, like in any other ethnicity, but also extends
between the medial cruras of the columella and spreads over the lateral
cruras, the supratip dorsum and the sides of the lower nasal wall; a
very meticulous defatting is a must, a very delicate maneuver that must
be carried out with great care not to damage the cartilaginous
structures and the overlying skin.
Another common finding is how weak, filmy and thin are the alar
cartilages in this ethnicity, they play almost no structural role, if
any, in the tip and alae shape, being the whole tip unsupported,
collapsed and its shape made out of the fibrofatty mass and the skin
itself; additionally the tip has no definition is too short and its
cartilages lack sufficient length to comply with the required
lengthening of the tip and the nose; for all these reasons the lateral
cruras are frequently discarded and replaced by new ones made out of the
cartilage grafts.
The tip and the columella also needed full replacement, therefore an
en bloc tip and columella extended graft can be sculpted out from the
rib or other source cartilage grafting.
Also septocolumellar or dorsocolumellar replacement graft augmented
with one extension to build the tip and another extension to lengthen
the columellar support down to the nasal septum; this structure achieves
longitudinal and lateral blockage with stability by pressure forces
between the radix, the dorsum, the septum and the interlocking between
the dorsal and tip columella parts, with lateral assistance at the tip
by means of the side pods formed by the new lateral cruras; no suturing
is required to achieve stability of this dorsocolumellar structure.
In the end, the whole dorsum, tip, columella, medial cruras and
lateral cruras are reinforced, supplemented or literally replaced by
handmade brand new anatomical elements allowing the expansion of the
skin cover.
It is remarkable how the septum is also massively short in these
ethnicities; this makes the septum insufficient as donor of grafting in
most cases and technically forces to some kind of septal lengthening and
nose lengthening maneuvers; this is sometimes accomplished by the
septocolumellar or dorsocolumellar structure which bridges over the
missing gap of septum, thus in such a case there is no need for direct
septal lengthening grafting.
Several methods allow rebuilding a massively missing nasal dorsum,
either by congenital causes like ethnicity or by acquired traumatisms or
iatrogenic dorsal over resections during previous rhinoplasties.
The alloplastic or synthetic prosthesis, made from Gore Tex, Medpor,
Silastic, silicone, polyurethane, etc., is a tempting option since it is
as easy as an out of the box solution, the surgeon only has to open the
sterile sealed package and insert into the nose, only in few cases a
slight shaving may be necessary to adapt the prosthetic dorsum to the
patient's nose; however this is the worst of all the available technical
solutions, to begin with it is unfeasible achieving an optimal fitting
on the dorsum, the prosthesis is noticeable through the skin, they look
pretty fake and unnatural, the rate of complications like infections,
displacement or extrusion are terribly high, they are prone to
dislocate, develop capsular contracture, extrude or become secondarily
infected during their lifetime, which actually is not indefinite and
will need replacement after a few years.
Fat transfer and dermal or fascial rolls are not suitable, they lack
volume to rebuild such noses, their look is weird, it is impossible to
shape the dorsum with precision and they are not consistent enough;
apart from the former they are prone to complications, infection and
resorption; they'll likely disappear in the postoperative or be short
lasting.
Bone grafting is not recommended, the rates of resorption are very
high and the look is not natural; the ideal material to rebuild massive
dorsal shortfalls is cartilage grafting, being several the modalities.
Irradiated human or animal cartilage from a tissue bank is not a
recommended option; firstly because it is not own patient's tissue,
making no sense when there are excellent donors sites available of safer
quality, however mainly because the rates of resorption, infection and
dislocation with deformities are very high with irradiated cartilage,
which in practical terms is a cartilage biologically destroyed by
radiation.
Ear and septum cartilage harvested from the patient's tissues are
excellent donors biologically but in the vast majority of cases not
valid because the available amount is scarce or their shape might not be
optimal; notwithstanding their use may be suitable in selected cases.
One popular option which deserves severe criticism is the so called
Turkish Delight technique or better named as diced cartilage wrapped in
fascia; it essentially consists in harvesting cartilage from the
patient's donor sites, commonly the rib, and crush down to tiny bits,
which means destroying the chondrocytes or cartilage cells and
annihilating any biological viability; once this jelly mass is obtained
the surgeon sticks the bits together by applying a synthetic fibrin
glue, rolling them in temporalis fascia or both; this roll is inserted
as neo dorsum, however the result is an avascular cylinder in which this
mass of crushed tissue develops necrosis, resorption, eventually
infection, irregularities, deformities, cystic phenomena, etc.; the
results are between poor and disastrous in the mid and long term, the
touch is fake like jelly and the dorsum experiences molding like it
would be clay with palpation or bearing the glasses pads.
The ideal option to massively rebuild nasal dorsums is own patient's
rib cartilage; in relative terms to the nose size it is an unlimited
source of cartilage, it is biologically compatible and safe since it
belongs to the patient, the likeliness o resorption, infection and
displacement are terribly low, is firm and strong enough to expand the
skin, is form stable, the touch and feel is natural, when it is well
tailored the look is totally natural, it should be lifetime lasting and
totally opposite to what many surgeons think it does not warp; the only
caution to be taken is harvesting straight fragments of rib cartilage
and not the curvy ones, and as additional caution peel off the cortex
and use mainly the core or central shaft of the cartilage, since the
cortex or outer layers have curvaceous streaks of cartilage making it
prone to warp.
In the case you post here the rib cartilage not only is an excellent
option to rebuild the dorsum but also may serve as donor for other
grafts required, like the tip and columella replacement graft and the
lateral cruras replacement grafts; the septum, otherwise very short, and
the ears remained untouched.
Once the rib cartilage is freed and the donor site meticulously
closed by means of layered sutures, the sculpting stage starts so that
the necessary anatomical elements can be restored in this kind of noses.
With the personal design I follow in these cases, one single fragment
of cartilage is shaped as dorsal rebuild graft with a hollow cylinder
carved in at the undersurface of such dorsal graft; this cylinder has
the purpose of providing stability by blockage obtained when the
patient's natural dorsum would be inserted within; this dorsal graft has
other very tricky and interesting geometrical features in its design,
like the beveled upper end to match the contour of the nasal radix and
the frontalis bone at the frontonasal sulcus, the slope gradient at its
lower end to prevent a supratip prominence or polly beak deformity, the
somehow imperfect broken contour at its sides in a very slightly
rhomboid shape to mimic a natural bridge and avoid a plasticized nasal
look, and the thin on top towards thick on bottom of dorsum gradient of
dorsal raise in order to create a correct nasal profile; at its caudal
end this dorsal graft is shaped featuring a cubic prong matching the tip
and columella extended graft in order to achieve interlocking stability
by perfect pressure effect.
Once the dorsocolumellar grafting structure is thoroughly tested and
deemed as definitive in terms of aesthetic effect and mechanical
stability, the final closure of the skin allows the assessment and
planning of the nostril sills resection and the alar flare wedge
reduction, is they are deemed indicated.
The smooth contour and the perfection of the tailoring of the dorsal
block makes often unnecessary additional camouflage with temporalis
fascia or specific blockage gestures to prevent its displacement, since
the final assembly is a perfect puzzle matching under pressure between
the frontalis bone, the original dorsum and the caudal septum.
Experience, fine skills and large amounts of creativity are of
paramount importance in order to successfully approach these complex rib
cartilage ethnic rhinoplasties.
See the link below to view a full series of images explaining the
procedure with real intraoperative and before & after photos.
If you wish better grounded opinion well lit, focused and standard
images have to be assessed: frontal, both lateral and both oblique
views, from underneath too.
Feel free to request any additional information from me.

The best way to determine what specific changes will look good on your face, and what changes are surgically possible, is to do your research to find the top Asian rhinoplasty specialists and consult with several of them in person.  During your consultation, your photos can be computer-morphed to show how the changes to your nose will affect your appearance.  An Asian rhinoplasty specialist will have the experience to determine whether the morphed images are surgically attainable.   Also, while there are several approaches to building up your nose during Asian rhinoplasty, using tissue from your own body will give you the safest, longest-lasting, and attractive result

Narrowing the bridge in Asian rhinoplasty is mostly related to elevating the bridge (dorsum) to provide a narrower view on the front.  Other techniques can also be used to narrow the bridge but in patients with thick skin (which is common in Asian women and men), much of the narrowing effect is created with raising the bridge with cartilage grafting or implants.  I prefer to use cartilage grafting personally since implants can be unpredictable and have various infection/extrusion rates but many surgeons use them frequently
The photo you show would be very difficult to achieve with your nose as the patient in the photos most likely has significantly thinner skin which allows the nose to look narrower without substantially raising the bridge height.  
An in person evaluation with a facial plastic surgeon comfortable with Asian rhinoplasty may be most helpful to you.  Preoperative computer imaging where the surgeon can morph your photos might help you understand what they may be capable of in your scenario.  Good luck!