Just the same landscape/architecture photography I do anyway. It's more than I made from Shutterstock. Probaly $100/year? So it's definitely on the level of "beer money."
Why have you chosen to upload photos to an "agency" that pays via donations? This doesn't seem like a guaranteed income for each photo that is licensed - particularly with the generous licence that pixabay places on each photo.
https://pixabay.com/users/derwiki-562673/