If you're only trying to solve the very narrow problem of entering a PIN to authenticate to the system, then sure. When you said "during keyboard input", I thou

If you're only trying to solve the very narrow problem of entering a PIN to authenticate to the system, then sure. When you said "during keyboard input", I thought you were being more general, but I suppose you must have meant during keyboard input of the system PIN. I don't think that PIN is the only sensitive information that matters, though. Android supports a numeric keypad input mode for apps. If I'm entering my credit card number into some app (Lyft, Amazon Shopping, etc.), that seems pretty sensitive. Maybe more sensitive than the system PIN even, because if I know your system PIN, I can't necessarily do anything with it unless I have physical access to your device or you've re-used the same PIN elsewhere.