I believe what they do is take the released version of stable diffusion and then continue training from there with their own image sets. I came across their attempts when looking into how to train the model based on some images of my own; their data set so far reaches between tens of thousands and hundreds of thousands images.
All the difficult parts (poses, backgrounds, art styles) has already been done by the SD researchers, the porn network only needs reference material for the NSFW description/tags/details. This is significantly cheaper.
A similar project, training SD to output images in the style of Arcane, is incredibly successful in replicating the animation style with what seems to be very little actual training data.
I don't think you need to start from scratch at all if you use the SD model as a base, all you need to do is to train it on specific concepts, styles and key words that the original doesn't have.
All the difficult parts (poses, backgrounds, art styles) has already been done by the SD researchers, the porn network only needs reference material for the NSFW description/tags/details. This is significantly cheaper.
A similar project, training SD to output images in the style of Arcane, is incredibly successful in replicating the animation style with what seems to be very little actual training data.
I don't think you need to start from scratch at all if you use the SD model as a base, all you need to do is to train it on specific concepts, styles and key words that the original doesn't have.