See Release zfs-2.2.0 · openzfs/zfs · GitHub
I have a build for Ubuntu 23.10 and 23.04 (patched to also support Linux Kernel 6.6) up at zfs-experimental : satmandu . I’m using it with docker (and overlay2) on Ubuntu 23.10/x86_64 with my own built 6.6.0-rc6 kernel.
It works for me.
Worth noting too that Ubuntu 23.10 has their own version of OpenZFS 2.2.0-rc3 included, and also that they have once again enabled zfs-root installation, though I haven’t tested that.