Not quite sure I understand this:
Are you taking about NethServer / Arm or about PFSense?
PFSense is a firewall. NethServer is a All-In-One Server.
Not quite the same thing...
Sure, in PFSense you can add in a USB-Disk and have a Instant NAS!
But they never mention anything about redundancy or RAID - for a good reason.
NethServer can handle that!
NethServer / ARM as home setup?
Depends: If you're OK using it as a fileserver without RAID, maybe.
But RAID on a Raspberry? It works, yes! But I/O... A single Disk works well enough, but for Home / Family use?
100 MB/S isn't enough for Media streaming in a home environment for 2 -3 users...
In my opinion, OPNsense as a firewall is better than PFSense, but this Forum isn't the right place to discuss that!
My 2 cents