Cutting the power is easy, the hard part is for the car to know when/how to reconnect power when the driver wants to start the vehicle. I guess with a physical

Cutting the power is easy, the hard part is for the car to know when/how to reconnect power when the driver wants to start the vehicle. I guess with a physical ignition switch, the mechanical motion of the tumbler could reconnect power. But, most cars don't have ignition tumblers anymore.