GPS uses a different frequency and a very weak signal. The antenna is typically separate from the others but it's very small <5 mm¹. It can be on the same board with other antennas with 3…4 cm separation between them. Also, we tested a GSM tracker and it still worked with a mismatched antenna. This was in Eastern Europe where cell tower power is quite strong. You have to completely remove the antenna and terminate its connection to be 100% sure. If you have coax cables with external antennas, you're lucky. The worst case scenario is when they're embedded in the infotainment system with amtennas and everything. This is also a cost cutting measure, so it's very likely to be used. The infotainment system is usually ideally placed under the windshield for undisturbed signal reception. But there is still hope to completely cover its back side and edges with aluminium foil tape.

1. https://learn.sparkfun.com/tutorials/gnss-chip-antenna-hooku...

Your cell phone could easily call for help in a crash without the car being involved at all.