I have aPBS server and my friend in a different geographic region has one. I backup to mine and he backs up to his. Mine syncs my backups to a data so l store in his, and his summer backups to a data store in mine. These are our offsite backups.

To be clear, we’re syncing our proxmox VM backups. But Proxmox Backup Server also has a client app, so I also back up my workstation to my PBS and it also syncs to the remote PBS.