I can dig it…but surely the simple option is to have the PC wake up on power restoration, right?

After the PC shuts down, the UPS runtime will increase by a lot. So the power might come back before the UPS turns off, so as far as the PC can see, the power was never lost.

Edit: Also I assumed you meant restore on after AC loss, and not the last state.

I found a post on the forum:

https://forums.truenas.com/t/scale-build-git-repo-going-closed-source/64313

This is only their old build system which they weren’t using themselves, the rest of the OS will remain open source. However they also said some worrying stuff about including “proprietary pieces of the OS”.