@CycloneSpirit ure able to just go into unity, body and show in explorer, copy and paste onto desktop, open substance painter drag fbx, and find the textures on the models and just put it where the tools/brushes are (drag it onto there) once youve made a fill layer and drag that texture to base colour (make sure ure on the right layer of the fbx too i have a bid that explains it better bc not alot of models especially if theyre put here will have its spp.
https://www.youtube.com/watch?v=jGus3UsrR6c&ab_channel=20nik