Wow this is very interesting! I think I will play around with the upscaler stuff. I have experience in C#, and a bit of python. If I can make some progress with this, then I’ll post here the results.
P.s.: Question is, that will it be a significant change if the textures were upscaled visually or not. Im not sure, since this way the UV’s remain the same, and didn’t really understood clearly what can be the limit of texture size. It surely would be a bit sharper, but that doesn’t worth all the time this procedure needs. I would probably go for character textures and landscapr ground textures, because those look the worst. Door and building textures are pretty decent by default.
Unfortunately, I don’t have an RTX videocard, so I can’t try that mod either.
EDIT: Okay, so I just read the tolich mod, and Vladimir Maestro answered the subject. It is nonsense to rescale textures, since those are hardcoded to remain the same resolution. So yeah, sadly its out of question.