https://github.com/kloenk/nix
https://github.com/shadowrylander/shadowrylander/blob/system/etc/nixos/flake.nix
https://github.com/colemickens/nixos-flake-example

https://github.com/Mic92/dotfiles
https://github.com/hlissner/dotfiles
! already mentioned at home-manager cfg samples

???
https://cfp.nixcon.org/media/nixcon-oct-2020.pdf
    https://github.com/tweag/nix-ux
    inputs.hello.url = github:tweag/nix-ux?dir=hello