I just want to ask if is it possible to make my phone lock when it sees person A's face. It's reverse to unlocking my phone.
It should work on all screens, whatever I'm doing, does that mean the camera is always accessed?
I'm not completely certain. I would think it would be theoretically possible, but it would greatly reduce your phone's usability and battery life. If you just bring up a barcode scanning app and notice how things slow down, I suspect a face locking app/service would be even slower. Also, you would probably have to be viewing the phone from a pretty wide angle so it wouldn't lock when seeing your face. It would also likely interfere with any video meetings or other camera based apps you wanted to use.