Considering the whole situation with Itch and Steam, I thought I'd point out something. GOG seems pretty supportive of adult games. They're talking about how their games are DRM free and owned forever, they were pushing back against the situation, and I saw that for two days they were offering NSFW games for free, including the very popular Sapphire Safari. It could be that they're just using the situation for PR, but I see that they actually have a lot of NSFW games on their store. Maybe it won't matter as much to this game, since it's not complete or early access like GOG allows, instead having a free version and a patreon exclusive paid version, but I thought it should be known that GOG is an option.
Viewing post in Corrupted Kingdoms (NSFW 18+) comments
https://stop-paypros.neocities.org/
Some resources for contacting MasterCard, Visa, PayPal, and Stripe and telling them to reverse their policy.
Doesn't matter for these types of games. You can't legally sell content built with Koikatsu assets because you cant lease them. That's why these types of VN's are FREE, but also with a Patreon early release. All content made with these assets has to be made free to the public at some point, or its a big copyright mess. So you wont see any Honeyselect/Koikatsu based adult games or VNs on any paid platforms/for sale at all. Its a donations based platform sort of legal loophole that keeps it within the realm of "fan content". (I'm not a lawyer, and that's a rough/over simplification for the situation of this type of content, so take it with a grain of salt. Tho I have been working on an unannounced VN)
TLDR- You cant legally sell anything made using koikatsu or honeyselect assets.