You clearly have no understanding of how Play services work.Except that the play store is absolutely riddled with malware and exploits such as side loading and FAKE BANKING APPS!
Google Play is not "riddled with malware and exploits".
Just like Apple, Google screens apps and on device security screens them again. Just like Apple, any app wanting access to your location, camera, microphone, etc., has to ask for that permission and the USER determines what an app can use.
Is it a perfect system, no. But what you describe is pure fantasy.
Anyone sideloading a banking app needs to have their head examined.