But you can try it's package manager nix and it's package set nixpkgs in any other Linux distribution.
> Because Nix (the package manager) & Nixpkgs (the Nix packages collection) can both be installed on any (most?) Linux distributions, they can be used to install NixOS in various creative ways. You can, for instance:
> 2. Install NixOS on the same partition (in place!), from your existing non-NixOS Linux distribution using NIXOS_LUSTRATE.
> /etc/NIXOS_LUSTRATE tells the NixOS bootup scripts to move everything that's in the root partition to /old-root. This will move your existing distribution out of the way in the very early stages of the NixOS bootup.
which is what the nixos-infect script does, because DO doesn't have native NixOS images.