Void Linux with ZFSBootMenu isn't far off. Multiple core Void team members uses and maintain ZFS support; kernel version bumps are blocked on OpenZFS support. ZFSBootMenu handles the bootloader, which can support fully upgraded ZFS pools and doesn't need pared-down zpool properties like Grub.

ZFSBootMenu is developed natively on Void, and their wiki has bootstrap instructions for a Void install with root on ZFS. Everything's well supported, including native zpool encryption. Plus gives you a multitude of tools right in the bootloader -- snapshot rollback/management, boot environment creation/management, booting older kernels, and a full recovery command line with zfs available. You can tweak the bundled dracut config to include other tools as well.

Even supports generating a unified, SecureBoot-signed EFI binary.

The experience is leagues ahead of the Ubuntu mess.