Volumes are horrible, how would I easily edit a config file of the programm running inside, if the container deosnt even start.

Bind mounts + ZFS datasets are the way to go.

I didn’t understand the docs either, that’s why I’m using https://github.com/girlbossceo/conduwuit insted

ZFS doesn’t require lots of RAM, more RAM just improves the caching (ARC) it can do. You can set ZFS to use all unused RAM as ARC, so it doesn’t interfere with other services running on the same PC. I ran ZFS with lots of VMs on an old office PC with 16GB RAM and it was still able to max out a 10gig nic.