Always remember: RAID is not a backup.

Having only one backup and the server dying means you now have no backup, therefore the 3-2-1 scheme for backups is worth looking into.

Not sure if it makes things easier than your current setup, but take a look at Mediathekwebview.de

The official NC docker container uses the “www-data” internally to run the services. This will get important if you ever want to run tasks via “docker compose exec”.