So, there are a lot of games that have 3D engines, one could use to make portrait pack, like for example Fallout 4 or Skyrim with the CBBE mod, could provide a good source for that type of thing. While there might be some issues with the monstrous races, but i belive i have seen mods that add beastkin/beastkin placeholder to the game, as well as it has sexmods, i know that there is one on LoversLab and there might be more.
While i personally do not have the time nor energy to do so, i wanted to float the idea, maybe someone more dedicated could take a stab at creating that type of gallery.
I mean, if there was also just a channel on Strive discord we could do so as a community, set standard for the pictures regarding the resolution, posing of the model and the description, which would then make it extremely easy to extract a portrait pack, that would also be sort of randomized, which is at least part of the appeal.