https://wccftech.com/google-assistant-will-now-let-you-use-app-specific-voice-commands/

Being an Android user for years, I have grown accustomed to Google Assistant to a point that I cannot even imagine using any other assistant aside from it. I actually tweaked the Bixby button to make sure that it always shows Google Assistant and I love it. However, the one thing that I never liked about the Assistant was that I could never ask it commands that were specific to apps. For instance, I listen to all my music through Poweramp. If I tell Google Assistant to play music, it would always play it through whatever app was installed as stock on Android. It was frustrating as I could never tell the Assistant to play my favourite songs or playlist using a specific app.

However, all of this is about to change. As a way to make Google Assistant more useful for everyone, the company is adding a lot of new features to make it better and more accessible. the feature that is making its way right now is going to allow you to open up, search, and perform frequent tasks across your favourite apps. All you need is an Android phone that has Assistant enabled on it. You will be able to open and search within apps using "Hey Google.".