I sort of guessed that. I'm not interested in doing it for money at all, but I'm interested in playing with the software and models a bit, 3D models in general. What do you happen to use for software, and why do you like it, if you don't mind the question. I happen to have a RTX 2070 Super, and it suits my non-heavy lifting needs.
I am really only playing around with this stuff, but from what I gathered, the software used is mostly DAZ3D to create the models and Renpy for the scripting. Some use Blender or port the models to Blender. I've installed DAZ3D and it is quite easy to put some models down and get them to take a pose and then render it. If you want to learn more about it, search on Youtube for IT Roy - he has several good videos on this (that I'm reviewing as well :-)