While Google Assistant is pretty powerful and does a lot of things right, its in-app integration with third-party apps has been patchy at best. However, that seems to be changing now as Google has started tightening the screw and bringing deeply tied, in-app actions to Google Assistant. With the recent update, you can now invoke in-app actions from third-party apps such as opening the Explore tab on Instagram, updating the profile picture on WhatsApp, and more. So if want to browse and add third-party shortcuts to Google Assistant then follow along.
Open the Google app and move to the “More” menu at the bottom bar. Now, navigate to Settings -> Google Assistant.
Here, you will find all the third-party shortcuts that Google Assistant supports on your smartphone. Keep in mind, the shortcuts are populated based on the apps you have installed on your device. Now, tap on “+” to add your favorite shortcuts and you will get a confirmation from Google Assistant.
So that is how you can add and run third-party shortcuts with Google Assistant. To be honest, this sort of feature was already there on Google Assistant, but it was not deeply tied or required extensive support from Google.