Is it possible to have an app block other apps even if you restart device?
Is it possible to have an app block other apps even if you restart the device?
Android provides the ability to draw over other apps (Tutorial here). In combination with an accessibility service, you should be able to detect when a user attempts to interact with a particular application and draw over that app.
The user needs to enable the permission though, so you can't really "block" the app permanently.
Source: I wrote an application that uses an accessibility service to detect Japanese Kanji in tapped areas in other apps. The app then uses the "draw over other apps" permission to show an info panel about the parsed Kanji.