@Wuzzy isn't the main benefit of LiberaPay that they do in fact also manage IBAN bank transfers? Seems like by far the best option if you are based in Europe.
@Modanung yes I looked into Gnu Taler, but it isn't really suitable for this. I really like the idea, but right now they are too stuck trying to get real banks on board and not making it easier for communities to run their own bartering systems or so based on it.
I did consider setting up Gnu Taler for a kind of "in-game currency" of sorts, where people donating to a project would get back an equivalent of GNU Taler based tokens to do various stuff with (mainly "voting" on stuff to be done or so), but after spending an afternoon trying to figure out how to host this in a way that this could be done I decided that without spending much more time developing specific tooling it wouldn't work. I still think it might be a good idea, but I don't have the time and motivation to do it myself.