[nordlicht]

So, just to clarify the current status with this retrofit:
I had it done today remotely by a Chinese contact in exchange for payment.

It works on a 2021 S6 with MIB3. The procedure involved updating three modules: 13 (ACC radar), 17 (instrument cluster) and 19 (gateway). Newer model years might not need all of these updated, but I'm not sure about that.

The control unit mentioned is not directly involved with the area view functionality, but is only necessary to hide two yellow warnings on the dash: "distraction warning unavailable" and "fatigue warning unavailable". It seems that the newer dash part 4K0 920 790 G (I have index E) either includes some new sensors for this functionality, or that newer model years have separate sensors for this (although from looking at a VCDS scan from a 2024 model, I wasn't able to spot anything to confirm that).

If anyone would like to have this retrofit performed as well, I can pass along the contact information of the person who did it for me.