Don't call them donations. Look at what reddit did: people can "give gold" to people for comments that they think were great. All it does is add some icon to a comment and put the person in a "gold club".

In games, people will buy so many visual improvements that add nothing but glam to their character.

Discord does... something, I can't remember what exactly, with their "turbo" and IIRC it costs discord cents, but the user pays dollars.

People will pay for the dumbest things. Give them a reason to sign up, add some kind of paid interaction that changes something visual or makes a dumb sound, add some tier system with context relevant names, and people might really pay.