Mostly adapted from here: https://www.reddit.com/r/truenas/comments/lgf75w/scalehowto_split_ssd_during_installation/
I am using a 500GB nvme as a boot+app drive, and don't want any mirroring for it. Most steps are similar execpt where creating the zfs pool
Here I need to get the partition uuid from ll /dev/disk/by-partuuid/
and use the symlink to execute next step which again wasn't a mirror config:
zpool create -f name-something /dev/disk/by-partuuid/<from last step>
zpool export name-something