I don’t think you need to get that fancy with it, I’ve had success with a similar strategy of cooking the burgers as normal, then placing slices of cheese on them with rhe door slightly ajar, and letting them melt with the residule heat

In airplane mode and even while turned off, phones have been known to still transmit data via background services. Leaving it behind, or a Faraday bag are the only assured options I’m aware of