I agree with the sibling; I think Apple's attention to UX is going to inform them that physical controls are good on a car, even if physical controls on the front of a phone (a la earlier iPhone models) are unnecessary.
I do assume it'll be a locked-down, walled-garden experience, only serviceable at Apple Stores (which will open garages at some locations), assuming they can get away with that legally. They'll reject any non-Apple-genuine part, of course.
But to your point about voice control, I do expect Apple will try to make that really good. Touchscreens suck for keeping your attention on the road when you want to change the heat temperature or change songs or stations. Physical controls are better. But good, painless, non-frustrating voice control is by far the best option for avoiding distractions and keeping your eyes on the road.
Given Apple's emphasis on UX and UI: 100% across the board. Ask any Tesla Model 3 Owner what they like the least about their cars, and you'll hear a lot of them complain about the touchscreen-only (sorta) interface. There's some levers and thumb wheels, sure, but I abhor my touchscreen-only interface. Love the car. Hate the UI.
Apple knows how to build interfaces. Including interfaces outside of software. I suspect it'll be the primary thing they focus on in the product launch video, how they didn't screw up the UI and there will be knurled titanium wiper speed ring switchy things and tactile feedback in the damn mushroom leather wrapped heated steering wheel and Jony Ive whispering directions, seemingly inside of your head.
This misses the point of the Tesla UI, which is to not be needed. Everything Tesla does is calibrated to minimize interaction with the perfectly functional UI.
I don't want Apple forcing their excellent design sense down my throat, I'd much rather have decent design I don't have to use.
As a big Apple user, I think all three are very possible.
Just one tiny example: see the manual dial or “crown” on Watch, AirPods Max, and now Vision Pro. You could easily imagine those products without an unnecessary manual “dial” when there is both voice (Siri) and software controls. But, you still have a “dedicated knob”.
a) You can operate it without talking to it
b) It has dedicated knobs/levers/switches for primary essential controls.
c) It doesn't require internet connectivity, continual tracking/telemetry etc.