I’m not quite sure what you’re trying to do here. Are you
- Trying to create a new owncloud instance and put your data somewhere other than in /var, or
- Try to move the data location of an existing owncloud instance?
If you’re trying to do the second one, there’s a useful guide on it here: https://omiid.me/notebook/25/move-docker-volume-to-bind-mount. The first one should be even simpler, you can just replace the volumes in the compose file by bind mounts (basically, just this step of the tutorial: https://omiid.me/notebook/25/move-docker-volume-to-bind-mount#modifying-docker-compose).
Gnome and KDE are not doing the same thing.
KDE will continue to offer an X11 session for the time being:
https://pointieststick.com/2025/06/21/about-plasmas-x11-session/
Gnome will disable the X11 session in the next release and then remove the code:
https://blogs.gnome.org/alatiera/2025/06/08/the-x11-session-removal/