This must have changed with 23.04 or something then, because when I set up my home server a little over a year ago, ZFS as root was not only not a part of the install, but also heavily recommended against as something that could be hacked in. Basically you could do it, but you shouldn’t was my impression. I ended up doing EXT4 as root, then mounted my ZFS storage in my home directory.
The last time I tried a Samsung phone I returned it the same day I got it. The competing OS elements from Samsung’s ROM and the standard Android UI were really really off-putting to me. I can get an app having a unique style, but this was different OS elements looking and working differently.