Why do you think using FreeBSD as a NAS complicates your life?
With a FreeBSD or Linux machine, even step one requires considerable thought. Are there web UI packages that I can use? Which one do I pick? Where do I install it from? How do I ensure that it runs on boot? Do I have to mess with the network configuration to ensure that http://mynas.local is accessible? How do I configure SMB? What's the deal with security updates? And so on, dozens of times over.
It's great if you're already in the depths of sysadmindom and know what you're doing, but man, I just want to put my files on some LAN drives and call it a day.
If you are looking to replicate the exact same thing(why would a NAS need a web ui), of course there is considerable work ahead of you.
I believe you are overstating how difficult it is to configure a FreeBSD box as a NAS. Configuring samba for example is a breeze.
The questions you are asking are good questions that are answered by the manual. Keeping FresBSD updated requires the use of two commands, both well documented in the handbook, freebsd-update and pkg.
Incidentally I actually found Truenas to be a solid upgrade from my old vanilla FreeBSD install; the tuned performance defaults made things a lot better for me after I recovered my volume (the USB stick I was using for the OS died).
So, its sad to recommend something else, or obviating it entirely.
"Just skip owning a car, just buy a nice pair of Adidas, they're easy to clean and don't cost much."
???
It's great for people who just want storage and don't want the heavy features that came with TrueNAS' move to Linux (Kubernetes, etc.) or who want full control over vfs_fruit options for serving Macs.
YMMV but for my use case I have my NAS hooked up to a TV in my living room that also works as HTPC, gaming console, and occasionally a spare PC for visitors.
But I'd be a bit worried about the availability of drivers for much of the hardware found on this particular motherboard.