NixOS
NixOS is an independently developed GNU/Linux distribution that aims to improve the state of the art in system configuration management. In NixOS, the entire operating system, including the kernel, applications, system packages and configuration files, are built by the Nix package manager.
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elementary OS
elementary OS is an Ubuntu-based desktop distribution. Some of its more interesting features include a custom desktop environment called Pantheon and many custom apps including Photos, Music, Videos, Calendar, Terminal, Files, and more.