On some cars you can also unplug whatever radio/modem doodad is responsible for phoning home. I have a Ford Maverick and disconnected the "telemetry module" which resides under the transmission hump by the front passenger seat.

I no longer receive updates to the infotainment system and I can't unlock the doors with my phone, but I also don't have the dealer emailing me service ads with my exact current mileage and tire pressure.