Help accessing EC2 AMI built using nixos-generators

Hello community,

I use a flake-based project to manage my NixOS systems. It is based on mitchellh’s one here. Anyway, I would like to add an EC2 image builder to the project. To this end I have used nixos-generators and added the the following to my flake inputs

    nixos-generators = {
      url = "github:nix-community/nixos-generators";
      inputs.nixpkgs.follows = "nixpkgs";
    };

and to the outputs

  packages.x86_64-linux = {
        amazon = nixos-generators.nixosGenerate {
          system = "x86_64-linux";
          modules = [
            # you can include your own nixos configuration here, i.e.
            # ./configuration.nix
             ({...}: { amazonImage.sizeMB = 60 * 1024; }) 
            ./users/jade/nixos.nix
            home-manager.nixosModules.home-manager {
              home-manager.useGlobalPkgs = true;
              home-manager.useUserPackages = true;
              home-manager.users.jade = import ./users/jade/home-manager.nix;
            }
          ];
          format = "amazon";
          
          # optional arguments:
          # explicit nixpkgs and lib:
          # pkgs = nixpkgs.legacyPackages.x86_64-linux;
          # lib = nixpkgs.legacyPackages.x86_64-linux.lib;
          # additional arguments to pass to modules:
          # specialArgs = { myExtraArg = "foobar"; };
          # specialArgs = {
          #   diskSize = 100 * 1024;
          # };
          
          # you can also define your own custom formats
          # customFormats = { "myFormat" = <myFormatModule>; ... };
          # format = "myFormat";
        };
      };

The image is built by issuing

nix build .#amazon

I then use a minor variation of this script create-amis.sh to make accessible on AWS (I am following Install_NixOS_on_Amazon_EC2

Unfortunately when I try to connect to an instance using the resulting ami I encounter this message

An error occurred (TargetNotConnected) when calling the StartSession operation: ...

I have no trouble connecting to the latest official nixos image ami-0826e43ab152a4208 (nixos/24.05.1791.4e6d12181cf6-x86_64-linux).

My hunch is that I might benefit from applying the content found in nixos/modules/virtualisation/amazon-image.nix such as

services.amazon-ssm-agent.enable = true;

and

  imports = [
    ../profiles/headless.nix
    ./ec2-data.nix
    ./amazon-init.nix
  ];

… I kind of expected this to be done by nixosGenerate { format = "amazon"; } above. Perhaps my home-manager module imports have messed things up?

Any guidance, suggestions, or thoughts appreciated!