As long as the Android device has cellular capability of any kind, even without a contract or cellular connection, it should have a compass, and the compass is usable. Oddly, on iOS, the cellular capability is the prerequisite for iPad GPS, but not the compass, as all iPads have compasses. With Android tablets, it seems almost all have GPS, but only the cellular versions have the compass, and it is not well documented that the noncellular Android tablets have no compass. Autel never intended for anything other than a cell phone to be used as the attached device, so these compass problems are of our own making for wanting a larger display device.
Even if you never fly out of sight, it is easy to lose the aircraft in the sky while looking down at the FPV composing your video, and the compass can be a very useful tool for finding it again, especially if you are traveling laterally across the area in front of you, and the FPV is lost, or not helpful, because of disorientation, or unfamiliarity with the location. Sadly, the controller itself has no internal compass (it's a $1 component), which means the problem is unsolvable when flying without any device.