To run the configuration you can type the following:
nix run github:mikaelfangel/nixvim-config
To include the configuration as a replacement for neovim you first need to ad it as an input on your system
inputs.nixvim.url = "github:mikaelfangel/nixvim-config"
Then you can input this in you configuration.nix (be sure that you inherit inputs from your flake)
environment = {
systemPackages = with pkgs; [
inputs.nixvim.packages."x86_64-linux".default
];
};
If there is something that you feel that is not quite right or you have ideas for improvment please submit a issue or a PR.