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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GNOME OS
GNOME OS is an experimental, immutable Linux distribution that ships the latest in-development GNOME desktop, core applications and stack. It serves as a reference for developers and testers.