About the SWIPE pattern: on Android 8.1 I can completely hide it. You don't see the dots, you don't see the drawn lines, you don't the pattern in case of error.

About the SWIPE pattern: on Android 8.1 I can completely hide it. You don't see the dots, you don't see the drawn lines, you don't the pattern in case of error. The only thing that I still cannot hide is the vibration when I hit a dot. I also specifically chosen a pattern that goes through the same dot two or more times, to confuse even more a potential observer. I tested it with friends: I let them observe when I unlock my device, and ask them to try and unlock it. Not one has managed to unlock it.