Not a bad idea, but you’d have to incorporate a time delay relay to override the oil pressure switch while the engine is cranking.
I’ve also designed a similar fail safe in my head to kill the ignition if the fuel pressure is not properly referencing.
Personally, I’ve decided to just go with the light that comes on when the second pump gets voltage, and to physically watch for the pressure jump when the 2nd pump comes on (on a regular basis, about once per drive, not literally everytime the car hits boost).