Could you please elaborate a bit on the appliance?

I use a home-grade PC with Ubuntu LTS on which there is nothing except for:

- docker

- borg (backup program)

- wireguard (VPN)

- sshd

I then copy /etc/docker from backup, mount some external disks with the data (either backed up or not for things I do not care about), reboot and I am done.

My recovery lasted one hour from starting the download of the ISO to being back on line.