I bought a U-Nas case a while ago. Just a small NAS-style PC case with eight 3.5" disk bays. I built it up and played around with it, but never put it into service in my homelab. It just sat there (off) with Truenas or something on it for testing. Well, it was a good thing I never did anything with it as I needed it the day my Synology died last year. It was a DS1518+ on (a lot of) borrowed time having lasted nine years. I mentally toyed with buying a new NAS, but the idea of spending a few thousand dollars didn't excite me (or the wife).
So, I loaded up Xpenology on a thumb drive and plugged it into my U-Nas. It did not take me long to see how easy this was to load up a Synology DSM and hit the ground running. Then, once I loaded all my disks in, it saw everything and asked if I wanted to upgrade the OS. Sure, why not?
So, all data intact and running a mostly generic set of hardware as a Synology only a couple of days later. Zero extra cost for me as I already had everything. But you can do this too with hardware you might have laying about. I highly recommend it.