Alt text: A line plot with 2 axis (confidence vs competence) referencing the Dunning-Kruger effect with various distro logos placed at different points on the line. Starts with mint/ubuntu near (0,0) and progressing through multiple distros to end up with opensuse/fedora at what it calls “the plateau of sustainability”
NixOS is a different approach to package management. Instead of installing packages using a package manager, you edit nix files (written in the nix language). Instead of changing individual config files for the programs and services you install (e.g nginx.conf or postfix.conf, each having a different syntax), you configure them using nix configuration files with a unified syntax.
There is a catch: your system becomes immutable and fully reproducible. Clone the file tree under /etc/nix from one system to another, apply it, and they become identical.
The configuration files are written in a functional language that allows you to customise your system as much as you like.
Read more about it here: https://en.wikipedia.org/wiki/NixOS
Edit: I actually use Nix on Fedora (you can install it on other distros without fully migrating!), and I use home-manager to manage my user environment and dot files. It’s pretty cozy.
Edit 2: and to answer the second question, I use it on my servers because it has comparable stability to Debian-likes while also being super convenient to use. A unified approach to server configuration is a win for me.
I hope nix and home manager become as easy to use and get the same reputation to non techies as brew is and has