Very deep tear troughs, do not want filler. Surgical or non surgical route? (Photos)

Since you haven't done anything yet to this region, I would recommend that you start slowly.
PRP/PRF/PRF gel are all great options for the undereyes. The risks of doing these are very low, the results are nice but not overdone, in the right hands, and can also help in collagen regeneration.

Fillers, which you noted you want to avoid, can be done, but a very smooth and thin one must be used for this delicate area. Despite the expectation that fillers (HA) will dissolve, they don't always, so that must be considered when using these anywhere but especially the unforgiving undereye region.

Fat can be a nice option but since you haven't done anything yet, I wouldn't recommend jumping into this potentially permanent option.

Sculptra is not intended to be used in this area though some providers use a more dilute solution for this off-label indication. I wouldn't jump into this option yet either.

Anatomically, the eyes appear to be significantly recessed backward. The eyebrows are protruding, while the eyes themselves are sunken inward.As a result, there is a lack of volume under the eyes, and the tear trough is deeply pronounced.There is a severe tear trough hollowing accompanied by protruding fat, creating a noticeable step-off that casts shadows, making the area appear more severe and tired.A surgical option to consider is lower eyelid fat repositioning. This procedure approaches through the conjunctiva to release adhesions around the tear trough and repositions the fat to fill the hollowed areas.Based on the photos, there seems to be limited fat under the eyes, so additional fat grafting may be necessary.