But, big picture, yes a lot of OSS projects have the same issue. Funding is clearly one aspect, but another aspect is also to work on having less "single person projects" (and I'm not talking about one time PRs but a genuine second core developer). I'm not sure how to encourage that however, maybe more commonly adding "HELP WANTED!" in the project README, maybe a button "I want to become a permanent contributor of <PROJECT>" button in Github, I don't know. If you are alone on a project, even if funded, chances are you will loss interest after a while, leaving the project with tons of possible improvements not realized, and a on/off maintenance, having more "N>1 core developers projects" would help mitigate that.