This is what I use to test it:

import ./nixos { configuration = { lib, config, pkgs, ... }: {
  imports = [./nixos/modules/virtualisation/qemu-vm.nix];
  boot.initrd.systemd = {
    enable = true;
    emergencyHashedPassword = "";
 };
  virtualisation = {
    graphics = false;
    memorySize = ;
    cores = 4;
  };
  documentation.enable = false;
  services.getty.autologinUser = "root";
}; }

Note that you currently have to format the nixos.qcow2 file manually for the qemu-vm

This is what I use to test it:

import ./nixos { configuration = { lib, config, pkgs, ... }: {
  imports = [./nixos/modules/virtualisation/qemu-vm.nix];
  boot.initrd.systemd = {
    enable = true;
    emergencyHashedPassword = "";
 };
  virtualisation = {
    graphics = false;
    memorySize = 4096;
    cores = 4;
  };
  documentation.enable = false;
  services.getty.autologinUser = "root";
}; }

Note that you currently have to format the nixos.qcow2 file manually for the qemu-vm

Aw, that decreased size was entirely because I switched to only including the necessities from util-linux instead of all of it, not because of the automatic dependency finder. And the finder didn't work well enough to actually function without significant help from manual inclusions :/

After staring at it and thinking for a while, I'm starting to think automatically finding Exec* stuff just isn't a problem worth solving. I imagine if a fresh set of eyes came to this project after this problem had been solved, they'd say any solution is way too jank to be worth it. If your unit file points to a program, then just include that program in objects... Adding services to initrd should be a fairly rare thing anyway.