This is exactly what I think every time someone recommends CachyOS or Manjaro to new users. Arch is great, but it expects the user to know how to deal with things, it expects user to read the news and it pulls the rug periodically because it expects you to be able to figure things out.

In your case in particular I don't think it was Cachy on its own, otherwise we would have seen other users affected, but still, it's likely that the Arch philosophy got you because of something you changed without even remembering and now with the update your config is no longer backwards compatible.

NixOS is great, but it's a very different paradigm, you will not be able to install things from the graphical interface as you're expected to declare your system. And it can never be compatible with a graphical installation as that would beat the whole purpose of reproductible builds.

I think what you're looking for might be something like Bazzite, where the core system is immutable but you get user space freedom. But personally, if 0 downtime is your goal NixOS is better, as you can rollback to previous generations of your system if something goes wrong, but to get that you have to pay the price of declaring your whole system which might be too steep to pay for some.