Immutable fedora works well for me.

I use this specifically:

https://getaurora.dev/

You use it to take the NextCloud files (set the NextCloud directory as a source) and Then you sent the files to a backup repository (destination).

You don’t send the backup files to a NextCloud install. That’s not the correct way to use the tool.

I self host a Borg repository in docker so the backup gets sent locally and then I also use borgbase as offsite backup.

You can have as many sources and destinations as you want

Borg backup is the way to go for this.

Its designed to have encrypted repos that are send to any destination remote or local.