This problem with proprietary screens can be resolved/mitigated with a cheap Android Auto/CarPlay dash-mounted remote display. They are basically a touchscreen tablet on an arm, with Bluetooth, an Aux Output and a cigarette lighter plug. There are cheap ones ($300) and incredibly cheap ones ($50).

I would recommend GM dealers (who don’t want to sell their franchise back to GM because this is a fucking stupid move) to invest in pallets of these things and give them away for free to new car owners who aren’t satisfied with the factory In-Car Entertainment.