It does. I have Alpine with ZFS storage drives, but my boot device is still ext4. Booting to ZFS is a bitch in a bitch basket. Grub doesn't support all ZFS features so you have to create a boot ZFS pool with only certain features turned on and never upgrade it. (I haven't actually gotten this working either).

I gave up and used btrfs as my root file system on a recent hard drive change. It's not as nice as ZFS, but I can still do snapshots and transfer them elsewhere for backups.