I doubt that this would be nearly as useful as you think since so many apps are dependent on Google services these days and even the client libraries for them are proprietary. And then there's the fact that you're constantly playing catch up with what is effectively a closed platform with no real public roadmap that throws the occasional source drop over the wall and says 'good luck!'

It's unlikely today's Google is going to be interested in seeing these efforts succeed. So an Android app runtime would likely only really run software from 5+ years ago well. Better to focus on making a really solid Linux mobile experience, IMO.