I believe I've seen a setting to setup a pin code to drive on my Model 3. You can also unlock the car with the cards that came with it instead of setting up the app on your phone and using Bluetooth. It would be a bit clunky, but it would work. There is also a keyfob you can buy (https://shop.tesla.com/product/model-3_y-key-fob), not sure if that uses Bluetooth or not, and is vulnerable though.