nixos-generate-config

See also https://github.com/NixOS/nixos-hardware.

Misc

To run it e.g. from Fedora, use:

sudo (which nixos-generate-config) --dir modules/hosts/anarres --flake

sudo chown vorburger:vorburger modules/hosts/anarres/*

Troubleshooting

Failed to retrieve subvolume info for /

This just means that you are not running it as root.