Mild hook nose - can I have pdo threads inserted to straighten and lift it.

PDO threads are not used to reshape the nose.   The only way of truly accomplishing this is a well done rhinoplasty.  Fillers can be used in a "non-surgical rhinoplasty" to add volume and accomplish some minimal changes (e.g. straighten a nose, remedy depressions, smooth out a hump, add some tip definition) albeit temporary.  PDO threads are used to temporarily lift the cheeks, the jowls and define the jawline.  They last from 6 months to a year.

Hello and thank you for your question.  The
best advice you can receive is from an in-person consultation.  Threads will not be accomplish this.  A rhinoplasty is definitely a better option for this.   Make sure you specifically look
at before and after pictures of real patients who have had this surgery
performed by your surgeon and evaluate their results.   The most
important aspect is to find a surgeon you are comfortable with. I recommend
that you seek consultation with a qualified board-certified plastic surgeon who
can evaluate you in person.
Best wishes and good luck.
Richard G. Reish, M.D.
Harvard-trained plastic surgeon

thread lifts are not defined for the nose, and the hook is bone, not tissue (so can't be lifted).  Be sure to discuss your goals and concerns with your board certified plastic surgeon and consider the pros and the cons. Be certain your surgeon is properly certified.  I've attached a link where you can start your search. 

You need an in person evaluation -- the last thing you want to do with your nose is insert foreign bodies. A well done rhinoplasty will give you the changes you want.

Threads cannot shave a dorsal hump or correct bony deformities. These require rhinoplasty.  See a board certified plastic surgeon who can propose an appropriate surgical plan.

Threads will  not be the best solution to treat your nose. It sounds like you would likely best benefit from a rhinoplasty, but you would have to be seen in person first to be properly evauated.