Linux Mint my beloved.
Linux
Mint's good; I'm on that right now. Regular Mint and LMDE aren't immutable though, and all versions are on a rolling release schedule. LMDE less so maybe, but it's still recommended to switch to the newest version before EOL.
Also, plenty of updates and software can go right to the bare metal or close to it. Some of those actually need to go there, even if everything else is run from Flatpaks.
The mutability factor of the given distros looks to be far lower, perhaps a step or two away from firmware on the "hardware through to daily-release-software" spectrum.
Interesting, I first heard about nixos from the self-hosted podcast. It seems like a neet idea and I do think I'll eventually try it out. It just seems like a lot to learn right now. To be clear, I'd prefer to use it on a server. Though, I may try it on a laptop first. Anyone with experience in desktop or server have any input?