If you don't have nix, follow the nix installation instructions.
Once you have nix installed, follow the instructions here to get access to flakes: https://nixos.wiki/wiki/Flakes.
After installing Nix, you can enter the local development environment by running nix develop, this will make the commands below available. Alternatively put use flakes into an .envrc file and use direnv.
Running deploy will execute the deployComamnd in Main.hs, in my case, it will rsync the resulting website onto the server.
Running check will start up the website on localhost:8000, the website will be updated live on changes to files in src, changes to ssg require a restart of check