I’ve got some standing orders of 1 or 2 euros every month for bigger projects like grapheneos and kde. And for small apps that I actively use, I try to donate 5 or 10 euros now and then. It’s not much but I believe if everyone is doing their part we succeed in the long run
I donate 0. I hope I’ll be able to do more once I get the new job. (I have a monthly donation budget, but it’s spent on other causes at the moment.)