This seems to have been an oversight on my part.
See from section
|
section('Add to existing Android app'); |
and on. In particular, reference the build.gradle for the host app
https://github.com/gmackall/flutter/blob/master/dev/integration_tests/pure_android_host_apps/android_host_app_v2_embedding/app/build.gradle
which is clearly following the instructions from the "module source code" section in
https://docs.flutter.dev/add-to-app/android/project-setup#add-the-flutter-module-as-a-dependency
and not the depending as an aar.