It’s not possible at all, no permission exists that lets an Android app record something in another app. Much to the sadness of the mobile Hearthstone community that would love collection managers and stat tracking apps like what PC and Mac have.
It’s not possible on Android, which is incredibly disappointing because I play a card game exclusively on mobile, and would love to use a collection manager and stat tracking app. These exist for PC and Mac, but not for mobile because of the very hard no-record-other-apps wall.
Also see the “autonomous taxi” services that, when encountering anything outside the limited scope their programming can handle, are remotely operated by human drivers.