This app was mentioned in 1 comment, with an average of 2.00 upvotes
In Bitcoin you can make one transaction containing multiple receivers ... this way you can save on transaction fees when making the donation once a week or so.
I used the same mechanism in my supporttr app https://play.google.com/store/apps/details?id=de.geektank.bitcoin.supporttr
Dogecoin can do this too - with even less transaction fee - so it would be a perfect fit.