Correct me if I'm wrong, but if I were actually to install this in my car, that car would no longer be street legal, right?
Without getting the new permission you are not allowed to drive it on public road. If you still do then you might also have the problem that your insurance is void.
I don't know what e.g. TÜV would say about a device like this, but I guess the outcome is it would be either to expensive to analyze it or not possible it all since the overall system design and the interaction between the different devices might be not be known (e.g. there might be no public knowledge on how Acura ECUs might react on CAN signals which were never considered during design).
Another way to say this is, there's nothing dangerous about the hardware. You could be using it as a logging platform for the data on the CAN bus in your car. But letting the software send commands and take control from a driver is a different story.
IAANAL, but I don't think even that is true. I think it actually is legal to allow it to take control of your car, provided you are still sitting in the driver's seat and can take control back at any time.
but if you're going down the highway and the AI decides to suddenly swing the wheel far right as quickly as possible, no human being would have reaction time good enough to recover without crashing. I'd be pretty concerned if you could add an autopilot to your car and drive it around on public roads without any sort of demonstration of safety.
"The EPS controller in the car limits the torque to a very small amount, so regardless of the message, the controller cannot jerk the wheel" [1]
[1] https://github.com/commaai/openpilot/blob/master/SAFETY.md
I can put a Chevy engine in a Ford, and plenty of people do much more than that, e.g. homebrew EVs, etc.
Can you GUARANTEE that you would be able to do this in a modified car with such a setup? You might be able to do so if we are talking about pure mechanical overrides. With blackbox software that's imho next to impossible. There will be no public documentation on what the cars systems will do if the receive some commands on the bus from a non-approved device and others from the driver. Even if you can observe through testing that driver inputs win the system might still behave different in some edge cases.