You could add a tag to feature request issues that it'd read from, maybe as a github app or something. I run an OS repo and it'd be really cool to be able to get through them all faster with a bit of money to pay a freelancer, for example. I imagine the users-paying side would be very hard to find though.

I'd also love to be able to attach a bounty to PRs with this money, although quality control would make me worry it'd be hard.

I imagine Patreon is never an enormous sum for people because the money is goodwill - it isn't tied to receiving anything back. You could make it like this.

I'm surprised there wasn't some other way of doing this - clearly other crowd funding sites exists, what do they use?