Any car that has a screen could have a built-in diagnostic tool displaying all the trouble codes, live data from sensors, etc. The computer behind the screen already has access to said data as it's connected to the various data buses.

But yet even in 2022 the best we can do is "service engine soon" and getting more information than that requires an expensive visit to the dealership.

I think there are apps that could read OBD-II codes? Though usually they're kinds cryptic and fixing them often beyond what an average motorist could do.

I wish I thought you were joking. With subscription services now needed to remotely start your car, we're almost there.

Shhhh... seriously; GM and others from the car industry might get the idea and actually implement such a travesty.