Yea that’s one of the things I liked about it. Your use of LVM allows that to a reasonable extent though. If your FS supports shrinking, you can even dynamically reallocate on the fly; which is what RedHat’s stratis system does to do ZFS-like things using only traditional block and FS layers, though requiring a daemon.
And btw, anyone interested in this thread may also be interested that @lheckemann did something sorta similar but very different with switch-root to boot an entirely different distro. I postulated in my ZFS blog post that it could be applied to boot any ZFS-supporting distro in the same pool, but never got around to trying it. He actually did it, and in a very interesting way.