TL;DR Access PVE host root filesystem when booting off Proxmox installer ISO. A non-intuitive case of ZFS install not supported by regular Live Debian. Fast full host backup (no guests) demonstration resulting in 1G archive that is sent out over SSH. This will allow for flexible redeployment in a follow-up guide. No proprietary products involved, just regular Debian tooling.
ORIGINAL POST Rescue or backup entire host