How would one go about this? I don’t see a way to donate to a bounty or create one.

You can use a generic OSS bug bounty market place, eg. Bounty Source.

https://en.m.wikipedia.org/wiki/Open-source_bounty

Which then take 10% off the top for administration of the platform. You cannot avoid funding administration, as that function enables the distribution of the money in the first place.

Of course distribution isn't free, but it can be made very efficient. So it follows that people will shop around.

That's a good solution, I might start doing that.