Just go to GOG. Yes, there is a curation process. But they have accepted a lot of NSFW games and are even having a NSFW sale right now with hundreds of games! Jast USA and MangaGamer might also take some in as well as Fakku and others.
I would not get my hopes up for gog too much. They basically have the same hurdles as Steam, judging from the available adult games there (and this includes regional blocks since a while ago). So better have a almost finished game and be a small company, I guess.
I wouldn't say that. GOG has everything from the smaller devs to the million dollar Subverse on there. As long as you have a game with a demo on Steam, you're fine. Remember, there are a few in development adult games there like Under Contract.
