I think there are more nuanced value conflicts around the workstation case. There's nothing wrong with the values you're working from, but they've slipped down my list over the past few years.
Nix can certainly be limiting in some ways. But everything can--we just habituate.
It's possible to find interesting tools that aren't at all cross-platform, or that require hours of DIY spelunking to get compiling, or that are only in some other repository. It's possible to find something you want to use that either isn't packaged for or is broken in every package manager.
I use Nix (on macOS and NixOS) for roughly the same reasons: convenience and flexibility. But from a different angle, I guess. It is freeing to know that everything I need to make forward progress on all of my personal and professional projects is specified. I have the flexibility to resume work on the projects I care about with almost no friction beyond securing new hardware.
I am finding that the Nix package manager on top of Fedora works nicely as a middle ground:
You can use it to set up a per-project nix-shell that gives you an experience a little like docker (in terms of speed), but more convenient because your normal machine is available on the PATH (or not, if you run --pure).
I can then use that same Nix config in my CI - just use the base Nix docker image and then apply the nix-env as a pre-script.
Nix can certainly be limiting in some ways. But everything can--we just habituate.
It's possible to find interesting tools that aren't at all cross-platform, or that require hours of DIY spelunking to get compiling, or that are only in some other repository. It's possible to find something you want to use that either isn't packaged for or is broken in every package manager.
I use Nix (on macOS and NixOS) for roughly the same reasons: convenience and flexibility. But from a different angle, I guess. It is freeing to know that everything I need to make forward progress on all of my personal and professional projects is specified. I have the flexibility to resume work on the projects I care about with almost no friction beyond securing new hardware.