promox is blocked from fully booting by ifupdown2 start job
inside the ubuntu live usb i am able use lvs to see the various lvm volumes; one of those is the root. these volumes are lists in /dev/pve/
since ifupdown2 is stopping the server from booting we want remove this from the system, we can do this by mounting /dev/pve/root to some directory, say /home/ubuntu/pveroot. then you can do chroot pveroot and run apt purge ifupdown2 and reboot