I’m a bit confused about what you actually want? Do you just want to update your packages, but stay on the same NixOS version? Just continue like before. Do you want to stay on your current version, but use some packages from the next version? That should also be possible if you somehow include that channel in your configuration.nix
(though I don’t know how this would work in practice).
Personally, I just run with unstable
though, then the releases aren’t that important.
I think I thought unstable would mean, well, unstable. Like nightly releases or something. Would you use unstable for Firefox?
I think unstable and the fixed versions use the same Firefox package, so you wouldn’t gain anything. The difference is rather in libraries that get used and how the distribution does things. For example, the changes listed in https://nixos.org/manual/nixos/stable/release-notes#sec-release-23.11-incompatibilities just appeared mostly one by one for me; one day, I wanted to update my system and got the error that the fonts option got renamed, so I had to change my configuration.
The fonts.fonts and fonts.enableDefaultFonts options have been renamed to fonts.packages and fonts.enableDefaultPackages respectively.
While when using a fixed point release, these changes won’t happen. Only when you switch releases. That’s what “unstable” refers to.