If it's free (as in, not even donations allowed) you can post all the porn you want. Folks still have paid NSFW content up though bc it's up to payment processors to catch them: Itchio is doing minimal interference after the first round of censorship because I think there just simply aren't enough bodies to do more.
So yeah, it works like every other art site, you just gotta be careful about paypros.
Speaking of: please join the fight! https://stop-paypros.neocities.org/