It will install to both A/B slots, and to the boot, and recovery partitions.

To be used like so:

 $ nix-build --argstr device google-walleye -A build.android-device
 $ result/flash-critical.sh

This is not documented as being "the way" to install on devices yet since this is almost unusable as it is right now.

The android-device output assumes a rootfs can be built. The current defaults cannot build a usable rootfs when cross-compiling.

This can be worked around like so:

local.nix

{ lib, pkgs, ... }:

{
  system.build.rootfs = (pkgs.runCommandNoCC "dummy-rootfs" {
    passthru = {
      filename = "dummy.img";
    };
  } ''
    mkdir -p $out/
    touch $out/dummy.img
  '');
}

Though, this points to a wart: this does not use lib.mkForce or anything similar. Using lib.mkForce seemingly does not work for system.build. I'm not even sure why this works.

TODO

• Make a usable rootfs when cross-compiling

Either through forcing a dummy image by default, or preferred, making a small "placeholder" nixos system that boots to an LVGL app in stage-2. (That LVGL app could be a hardware test app...)