(Unfortunately this funding opportunity is only for people with a residence in Germany. But if that applies to you, read on.)
Since two weeks now, I am working away on a food edibility informer software that is funded via Prototype Fund. It feels just right: I can work on an environmentally and socially useful tool, and I even get paid for it by German government 
Work is very self-directed and free, and from wherever I want, and at 50 EUR the usual hourly rate is decent. There is some annoying form filling and a bit of reporting, but itâs manageable and Prototype Fund has hacked the German governmentâs grant system enough in the previous rounds to make this comfortable for bureaucracy-averse hackers.
The good news is, there are more rounds, open for applications twice a year until March 31, 2024. (Maybe there will be even more rounds after that, as the initial 4 year runtime was already extended by another 4 years.) You basically get paid up to 6 months full-time work on a socially relevant open source software idea of your choice. It can be a completely new thing, or (as in my case) an extension of an existing tool towards a new use. From what I have seen, each round draws about 200 applications, and 20-25 get funded â so the odds are pretty good!
For all the details, see here (in German):
In addition, starting 2022-04-15, there is a variant of this for open hardware projects, the Prototype Fund Hardware:
And finally, there is also a version for residents of Switzerland, funded not by government but by a foundation: