To check if the backups are actually ok? Did you know most people do not actually perform restore tests.
If I would do this, I would spin up a isolated docker container to restore the backup. This docker container would be destroyed after a successful restore. This new container would not be allowed to communicate to the outside world (e.g. not send any emails, not download new content, etc.).
Restoring a backup could be a simple docker exec with the commands
discourse enable_restore
discourse restore <backup>.tar.gz
But you need the same container image for the site to verify… So maybe a image rebuild after the restore? and then verify.