If you need Linux compatibility layer AND ZFS without a hypervisor, unfortunately it's hard to get close to a Linux host. I've never used FreeBSD or SmartOS in production (I did use Solaris and zones in the past) and I know ZFS support is first class in those. But I've been using both zfs-dkms and kmod-zfs in RockyLinux and the experience has been pretty pleasant (ended up chosing kmod because we only follow OS releases anyway and install time is better there). I'm sure the story is similar for OSes like AlmaLinux (which also get upgrades sooner than Rocky, and I would prefer to use it instead of Rocky, but it is a requirement for us).

On my desktop I also use ZFS with kmod on cachy and updates have been seamless so far.