I’ve never had an issue as long as you have nested turned on. I don’t think it needs to be privledged for that

Good write-up

TrueNAS (ZFS) needs direct access to the drives. Typically a software raid is considered to be more reliable/flexible since with ZFS it also checks for file integrity. You can set several variables to add to the integrity as well as special vdevs to help speed things up. Integrety comes at the cost of storage, so make a plan for how much storage you need versus how much data integrity you need.