Here’s an uncommon setup for you: root on ZFS on NVMe on a Raspberry Pi 5. This worked after I figured out I needed to install the zfs-dracut package, which unfortunately depends on dracut, so I had to work around that.
System:
Raspberry Pi 5 Model B Rev 1.0
Root mount:
rpool/ROOT/ubuntu on / type zfs (rw,relatime,xattr,posixacl,casesensitive)
Boot mount:
/dev/nvme0n1p1 on /boot/firmware type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,errors=remount-ro)