While I am not an NSFW creator or even consumer of such games, I have been following this situation for a while so will try to answer your questions.
For the first - from what I have seen, so far there is no specific community that tackles that issue but individuals have been pretty vocal on Bluesky and following the whole situation, though I hope community bands together somewhere to at least help be more informed.
In terms of the second - there have been a few attempts at making a difference. For Americans, there is ACLU petition. There is also change.org petition though I wouldn't have high hopes with that one. For EU folks - Digital Fairness Act looks for feedback, which means the issue of the whole situation could be brought there and the plea to introduce protections into the DFA against payment processors and card companies using their power to make threats of cutting business if not complying with their personal policies.
In terms of the third - at least for now, there are no alternatives that could offer actually selling your NSFW game like on itch. DLSite is strictly Japanese and has been hit with similar stuff to itch and F95Zone that I have seen some people mentioning is just a forum. I guess the closest alternatives would be either already hit Steam or if your game is web based and don't mind posting for free, try your luck at Newgrounds (they allow adult content as long as you tag it, so there is that).
If I will get any additional info in terms of those 3 questions, will be glad to add up more info.