You and I must have a different idea of "fire and forget." I've been running my NAS on a generic Dell running stock Debian for over a decade now, and I've never had to get the soldering iron out to maintain it!
Still, other than replacing old drives, something that'd happen regardless of solution, that's the only fiddling I ever had to do.
https://news.ycombinator.com/item?id=13585048
https://www.auvik.com/franklyit/blog/vendors-clock-signal-fl...
I should start investigating potential migration paths that would allow me to do a HDD migration as that would be ideal. Although it looks like that might be a pain due to some of their OS-level limitations.
And actually a good reminder for me to eBay up another cold spare, because I totally forgot to.
Instead I bought a lower end Synology & stuffed it with some HDs, and it's been pretty fire & forget while satisfying all of my needs. I'm able to mount drives on it from all of the devices in my network. I can use it as a BitTorrent client. I use it to host a Plex server. And a few other odds & ends over time.
Meanwhile the only issues I had were needing to solder a resistor onto the motherboard to resolve some issue, and replacing some HDDs as they were aging out.
All in all it has struck a perfect balance for me. I'll grant that "solder a resistor onto the motherboard" is likely beyond a typical home user but it's also been a lot less fiddling than some home-brew solution.