Honestly, you could be absolutely right. I haven't revisited Nix since Bazzite Buzz #12 informed us on the following:
"The Nix ujust script has also been removed due to conflicts with SELinux policies. Users can still install the Nix package manager manually if they so desire at their own risk."
However, the above could be outdated; I simply don't know. Are you aware of any developments that have changed things for the better?
So, the basic premise of the impermanence module is to flush all state on (re)boot. By default, NixOS is already capable of rebuilding your entire system from the config file(s). The impermanence module simply aids in achieving the desired system workflow for no state without reinventing the wheel. In effect, It's as if you've just done a reinstall and setup everything as you like. But you get to experience this on every reboot. For someone that's perpetually disturbed by state, which has been the case since my Windows-days*, this would finally grant me a peace of mind that I've been yearning for years. So, to answer your question, it would help me get (at least one step) closer to stateless Fedora Atomic without giving up general usability.
You would have been right if the entire filesystem were to be immutable. However, for Fedora Atomic, /var and /etc are writable. Thankfully so, as most people wouldn't want a totally locked down operating system. Heck, no general-purpose distro (or OS otherwise) tries to achieve that level of immutability by default.
lol. I initially had a better written reply that I was about to send, but I clicked on cancel instead of reply. RIP.
First of all, thank you for sharing your own experiences!
Secondly, in short, looking at the discord servers that are related to the uBlue project, general folk seem to have moved past Nix and use flatpak and brew instead for GUI and CLI respectively. Though, some community members happily report to be content with Nix. So, perhaps I shouldn't be necessarily opposed to home-manager.
Finally, I didn't expect to find a crossover between brew and chezmoi to effectively become a quasi-home-manager.