Hey, about the itch situation — instead of just sending a Drive link to people who bought the game, you can use itch's own free key system. It's better because the buyers keep the game in their itch library and get future updates automatically through the itch app.
Here's how it works: even if you switch the page to free, you can still go into your game's dashboard on itch and generate individual download keys. You send one key to each person who already bought the game, and they get full access to the latest version like normal.
For new customers, since itch can't process NSFW payments anymore, the most solid option for one-time purchases (no subscription) is DLsite — they handle adult content and their payment processors are fine with it. Steam is also possible if the game passes their review, and it has the same kind of free-key system for existing buyers.
One thing to check: itch sometimes limits how many free keys you can generate depending on your account, so it's worth messaging itch support first to confirm you can make enough for everyone who bought it.