I'd just like to interject for a moment. What you're referring to as Nix, is in fact, NixOS, or as I've taken to calling it, Nix plus OS. Nix is not an operating system unto itself, but rather another free component of a fully functioning system made useful by the boot loader, initrd, and service manager comprising a full OS.
Many computer users run a modified version of NixOS every day, without realizing it. Through a peculiar turn of events, the version of NixOS which is widely used today is often called Nix, and many of its users are not aware that it is basically the NixOS operating system, developed by the NixOS Foundation.
There really is a Nix, and these people are using it, but it is just a part of the system they use. Nix is the package manager: the program in the system that builds the executables to run. The package manager is an essential part of an operating system, but useless by itself; it can only function in the context of a complete operating system. Nix is normally used in combination with the NixOS operating system: the whole system is basically Nix with an with OS added, or NixOS. All the so-called Nix distributions are really distributions of NixOS!
