Is it possible to patch an application in Android at runtime and create a new Application?

Question

linux

Hello.
I stumbled across the open spaces of the play market for some application with strange behavior.
After downloading from the store, at the first start, the app crashes (always). On the next visit, instead of a real application, a webview with obscene content is shown.
Attempts to reverse engineer the APK led to the hypothesis that this app finds another application class in the additional Dex file through reflection, receives it through reflection and starts.
The most interesting thing is that if you put .apk just like that, not from the store, then a regular application is shown. Some kind of forbidden magic is going on ...
Maybe someone has come across something similar? Wildly interesting to know the secret of this apa. Is it even possible to start another application through reflection?
Many thanks in advance for your comments.

Answer 1

Run another application by passing its parameters - yes.
Run anything inside yourself, packed horseradish understand how - yes.
Patch third-party applications on the fly - yes, but this requires the appropriate rights.
Most likely, the webview just opens when the trigger is triggered, but it works as it works to complicate the reverse.