Use two fingers to put in your PIN
One actually presses, the other one doesn’t
You could generate an absurd amount of possible PINs that could work on your card, giving any PIN peepers a seriously hard time, should they somehow have the intent to get ahold of your card and PIN through spying and pickpocketing
Safes, doors, etc. same principle
Even better tip: commit your false finger movements to muscle memory so not even a recurring stalker can bypass it
This will be totally overboard, and totally unnecessary, most of the time. But like any kind of security, it’s good to have it even if you hopefully never need it
You can do the same on a keyboard. Use your left hand to lightly tap the 1234 keys while actually typing out the characters with your right. Saved me when I had to sit next to some nosy kid once.