The best I ever saw, or tie for 1st anyway, was that the car wouldn't start unless the blower switch was in full-blast & AC was off. As far as I know, the HVAC worked normally after starting. I suspect that the full-blast position no longer went to the blower motor but supplied power to the IGN-ON relay or fuel pump, though I didn't get the full details of wiring on it.
Tie / runner up is my old man's car. Again, I don't know exactly how it was done but you have to press the garage door opener buttons, in the correct sequence, in order to turn on the fuel pump. Door opener also works to open the garage door & is kept in the map pocket on the driver's door.
Third best, IMO, is the hidden switch wired in series with the ignition key to supply power to either the fuel pump or fuel injection relay.
Noise alarms are good for nothing but pissing off your neighbors.