The vehicle no longer has an infotainment CAN bus in the traditional sense.
The MMI is connected to the gateway via MOST (MOST ring).
Connect the AI to the gateway via CAN.
If you want to send something to the AI, there needs to be another gateway between the AI and the first gateway, which relays everything from both sides and modifies the data from the two upper lines if necessary.
The MMI control unit is connected to the MMI via a serial connection, with the initial MMI3G using 9600 Baud, the next version using 19200 Baud, and only with MIB is there a private CAN bus.
Checking the control panel is very simple; I once created a complete list of commands for it, but unfortunately, I can't find it anymore; it's been 7 years

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Your plan is feasible, but it will also be complex and time-consuming.