One of the largest motivations for users to donate to open-source projects is for their funds to be used directly for features that benefit them. Is there a service that allows users to "pledge" an amount of money for particular GitHub issues that are cashed out upon marking them solved?
You can see how the bounties are labeled here: https://github.com/evhub/coconut/issues
When you complete the PR for the issue, you then fill out a form with Open Collective and they transfer you the money.