It appears Linux root-on-ZFS is a mess. No standard way to do it. Kernel updates require recompiling ZFS. Boot environments are a cornucopia of constantly evolving hacks.
If you're actually using #ZFS on root, on #Debian, what's your preferred hack to make that happen? #sysadmin
I suspect #openzfsmastery might need to assume root on extFS and data on ZFS, leaving root-on-ZFS for the advanced user or a terminal chapter. 
@mwl I stole scripts from proxmox, which does a clever thing where they have the efi/boot partition on every disk in the vdev, and then they add a debian hook that installs the bootloader and copies the initrd to every single one of them whenever that changes, ensuring that any disk that survives an untimely death can boot the system correctly.
It also implies they have a lot of extra glue for all of these filesystems, and that in its absence, you have to deal with that yourself, which is annoyingly involved.
Which, I think, mostly reinforces your point
Michael W Lucas 
mr_daemon