I miss data to confirm any of this does significantly improve security.
replyAnecdata: I have yet to meet someone who have been targeted by unknowingly side-loading apps.
If they really want to improve security they can work on much more impactful changes. I know people having been scammed by ads proudly delivered by instagram and google. I read about malicious apps that somehow went through official store filtering.
They're doing good work on those fronts as well, but in war you don't win all the battles.
replyIt's also especially difficult to tighten security in the direction your money is coming from.
Android has no such constraints