I flat tow a 2019 Buick Envision with Keyless ignition behind motorhome. This procedure I use; Push button to start car, hold brake and shift car into neutral, Push button to turn off car. If I am towing all day long I remove fuses 29 and 32 so not to drain car battery.
Was thinking about trading vehicle this year, but the newer Envisions can not be flat towed.