these are the zfs mount and unmount commands based on this: https://github.com/zfsonlinux/zfs/wiki/Ubuntu-18.04-Root-on-ZFS#troubleshooting mount: https://git.io/Je0e0 unmount: https://git.io/Je0eu

zfs_mount.sh

                      #!/usr/bin/env bash

zpool export -a
zpool import -N -R /mnt rpool
zpool import -N -R /mnt bpool
# skipping first rpool/ROOT and initial root (i.e. rpool/ROOT/ubuntu), because doesn't have tailing '/' so grabs numbers
zfs list | grep ROOT | tail -n+3 
zfs mount rpool/ROOT/ubuntu
zfs mount -a
mount --rbind /dev  /mnt/dev
mount --rbind /proc /mnt/proc
mount --rbind /sys  /mnt/sys
chroot /mnt /bin/bash --login

zfs_unmount.sh

#!/usr/bin/env bash

# get out of chroot
# type exit or Ctrl + d
mount | grep -v zfs | tac | awk '/\/mnt/ {print $3}' | xargs -i{} umount -lf {}
zpool export -a
reboot