With rear you can back up your system to pretty much anything. Mounted volume, USB drive, even to a bootable iso.
I use weekly rear backups for my system, and hourly Borg backups for diffs/point in time restore of user data, but you could use rear for an entire system snapshot as well.
Relax And Recover for os level backups. https://relax-and-recover.org/
With rear you can back up your system to pretty much anything. Mounted volume, USB drive, even to a bootable iso.
I use weekly rear backups for my system, and hourly Borg backups for diffs/point in time restore of user data, but you could use rear for an entire system snapshot as well.