It depends on exactly what you mean by check the content. If you want to browse the snapshots to see what files/folders they contain, and you’re on linux, macOS or FreeBSD, then you can use the mount command to mount an entire repository, and then look through the snapshots in it and their contents as if it were a regular filesystem. restic mount is discussed in the restore section of the docs:
If you’re on windows, then mount isn’t available, so I think you’d have to fall back on viewing a listing of the contents of the snapshots. You can do this by running restic ls <snapshotid>. While this is also briefly mentioned in the restore section of the docs, the manual has more details.
“Checking the content” means:
Browsing your backup as a regular file system
Therefore restic’s Restore using mount is the relevant function.
However, all snapshots are stored in Nextcloud, means there’s no local storage like /srv/restic-repo.
So, the question is:
How can I mount the restic repo in my Nextcloud WebDAV storage?
By using exactly the same command as in the docs, but replacing /srv/restic-repo with your repository location.
I believe as you’re using rclone, the mount command will therefore look something like this:
restic -r rclone:<remote>:<path> mount /mnt/restic