Patreon seems like the next best thing that has peoples' cards and their cut is 10%.

Credit card fees alone were universally 2.9% + some cents last I checked.

It's interesting that GitHub takes 0%, but that's clearly subsidized by something and I'd like to know what before I sign up to that ("clearly," because of transaction fees they're paying).

10% is a reasonable cut if they can help maintainers get from $0 to $1 and beyond.