I thought I would answer to some of the comments here.
> It's their place, their rules
Definitely true. And I am not going to try to go against those rules. But I believe I am allowed to voice my opinion about them.
> Use in-app purchases instead
This is definitely a valid option, but that requires diving into Google Pay, which from what I understand is not the easiest API to work with. It also means I have to maintain additional code for Google Play. More not-so-fun work to do for a side project.
> Make it a paid game
Another valid option, but given how everybody is used to free games on Android, I doubt it would get much success. It also does not help that Google Play disallows switching a published app from free to paid and vice-versa: it's a one-way decision.
I might end up going that way though, because it has the advantage of not having to write store-specific code. Pixel Wheels is not Android only: it also works on Linux, Windows and macOS, so not having to deal with store-specific requirements gives me more time to work on the game itself. The game would still be available for free on F-Droid and for pay-what-you-want on itch.io.
I also happen to run other open-source projects, and my goal with donations is to get people to support this open-source work, not just my work on this particular project. I don't expect to ever live from this: in my wildest dreams donations would let me spend a work-day per week or every two weeks to work on open-source projects.