Just a short update:
There is now a special icecast.docker-compose.yml that allows you to use the remote streaming capabilities of Raveberry with one command.
I finally implemented sensible logging, so error messages actually end up in their dedicated files. For docker and the console version they are also sent to stdout for better access.
Per request, Youtube can now be disabled in the settings. If you only want listen to listen to your local sound files, this keeps those weird music videos away from you.
Have a good day!