if putting in a kill switch, don't run it to a factory switch. In my Fox I added a kill and some other anti theft measures. Initially I was going to use the fog light switch (I don't have fog lights). All a thief would do is fiddle with all the switches. I put in a sneaky fucker switch almost impossible to find even with trained hands.
My van is also a target vehicle and thieves looking for them have been known to bring their own ECU and do a quick swap. A cage slows them down. Also other measures taken but it has a fob/push button start.
I'm looking after a neighbors place, they've been gone for a couple months. I move the Range Rover (a supercharged weapon) to feint occupancy of the house. I went to trickle charge the battery of another vehicle in the garage. Fob wouldn't open it so I assumed flat starter battery. I used the emergency key in the fob to do a whole intricate dance of manually unlocking the door only to have the alarm go berserk once open. Loud AF inside the garage. I then had to figure out how to crack open the intricate fob, find a 2032 and silence the racket. Ahh progress.
The whole fob/push button start feature is another layer of unnecessary complexity that opens the door to this stuff, in addition to introducing more failure modes during normal operation. This new cool feature costs more to produce, and adds to purchase cost.
Give me an "old fashioned" real key with tumblers like my front door, but that ship has sailed.
I expect India or some other upstart to make a bare bones, manual everything ICE powered car that comes in around 10K. It'll elbow in and steal market share with all the car buyers trying to use low buying power inflated dollars looking to buy groceries instead of a ball and chain car loan.