I don't see why this could not be possible on Android. All Google needs to do is build an API for Assistant that other apps can use to 'donate' frequently used actions/intents. Assistant can then make suggestions to users based on its own analysis of users' activities in the same way Siri does.
I am seeing a trend in this thread, that people think that Google Assistant doesn't have something whereas in reality it has already implemented all and more than what Apple did this year. Either, they are biased and are making assumptions, or they use Siri and are again making assumptions . Partly, another reason might be that Routines is within the Assistant Settings so people haven't discovered. Still, seems odd at a site like this. Frustrating.