I have a steam deck, and while its somewhat portable, I wouldn't want to carry one just to use at a charging station, considering the alternative is a controller stashed away in the glovebox. Probably also would want to carry the deck whenever leaving the vehicle too, considering how common it is in certain regions for some tesla models to be broken into and boot emptied out (apparently preventable with a 3d printed shim).

With the crazy powerful GPUs in these cars IMO it's practically free to enable this functionality for the user when the car is stationary, on a screen that is much, much larger and with a nicer sound system compared to any handheld or phone