In the wake of itch.io's delisting of nsfw games, I had a few conversations in game development Discord servers about the situation. In one of those conversations, someone suggested an upcoming payment processor called Taler, which is developed by the GNU project.

It's a privacy-friendly, open-source payment infrastructure which isn't based on blockchain. It bills itself as "a payment system that makes privacy-friendly online transactions fast and easy." However, it's not yet ready to be adopted:

Are there any projects already using Taler?
We are aware of several businesses running exploratory projects or having developed working prototypes. We are also in discussions with several regular banks as well as several central banks about the project. That said, there are currently no products in the market yet, and we believe this would be premature given the state of the project (see also our bugtracker for a list of open issues).