You cannot afford to risk mixing software like Poser with Stable Diffusion unless you own both. If later on Stable Diffusion is outlawed or it is shut down for any reason, Poser would be left useless.

FaceApp ended their face swap feature because of legal issues. Their rating dropped to the point where they don't have much left before they have to close up shop. Lot of AI apps are dropping like flies.

I think what you are looking for is post-processing. Take your Poser render and go to a A.I. website and ask them to improve the render. They'll charge you for it, but you got your amazing textures and everything.