a great number of people made suggestions (thank you everyone who took time out of their days to write some stranger to help them!)
I decided to go with @codeberg - it is a hosted Gitea instance backed by a german "Verein" which is a construct I think is well suited for what I'm looking for. They are financed by donations and (apparently voluntary) memberships.
Find me at https://codeberg.org/ccoenen
chaos.social – a Fediverse instance for & by the Chaos community