there's ~~[email protected]~~ (German, so probably not helpful), [email protected], [email protected], [email protected] and probably a lot more.
If you have trouble joining any of these, you can always search for the link on your server and the server will look them up.
Also there is a tool that has all communities in one place: https://browse.feddit.de/ But then you have to search for the name anyways ;)
Is that a start?