Hi,
If you want to use new backup system and store backups on the remote server then the backup server must support OpenSSH and rsync.
OpenSSH and rsync are supported by any Linux distro (Alma, Rocky, Debian, Ubuntu, etc). OpenSSH and rsync can be running on Windows OS too. So there is no strict OS requirement.
Backups can be restored by the admin (root) only. The CWP user doesn't have permissions and options to run the restoration process.