I have 2 problems with integration of shortcut's capabilities (but the shortcuts themselves work properly) in Android:
If I clearly understand it will be able after publication at the Google Play, but my application is not designed for this store. How can I force Google Assistant to understand my queries?
For app actions, your application needs to be uploaded to the Google Play Store. That being said, it doesn't need to be published to everyone. At the very least you can create an internal or closed test release.