nixos-generators/formats/install-iso.nix

{
  lib,
  modulesPath,
  ...
}: {
  imports = [
    "${toString modulesPath}/installer/cd-dvd/installation-cd-base.nix"
  ];

  # override installation-cd-base and enable wpa and sshd start at boot
  systemd.services.wpa_supplicant.wantedBy = lib.mkForce ["multi-user.target"];
  systemd.services.sshd.wantedBy = lib.mkForce ["multi-user.target"];

  formatAttr = "isoImage";
  fileExtension = ".iso";
}