Scenario: you’re using opensource software and you aren’t donating yet, however you have enough money left over every month to do so. Something(s) is holding you back from donating. Think about what that is and what would have to change for you to change that.
I think I’d have a hard time picking out single projects to support. I sometimes do one-time donations to things I like (for example I donated to LocalSend one time when I discovered it and liked it a lot).
I have a regular donation to the Electronic Frontier Foundation though, which I feel sort of covers the same area in a more general sense.