I adapted few keys from older A6/Q7 with Smok immotool, but this MY will not work with Smok anymore. All keys was bought from dealer. I tried a few weeks ago a similar MY car and after attempt my hw-id shown was scrambled, luckily i did not hurt more. So i think there is no easy "OBD solution" anymore for MY2010+. Anyway you need a prepared key, so first of all you need data from EZS, which is immo master in these cars. It´s a very ugly job to dismantle the the PCB.

It´s useless to disable immo in ecu, if you mean this. You will still have no ignition, no steering lock release, no starter release, no tcu release, etc.

You can swap the ECU and defeat the immobilizer in the ECU, but it has absolutely nothing to do with the key.

It is possible to swap whatever, if you have ODIS with a GEKO subscription. There's tons of people doing this coding remotely too with the original software, because it is possible to do so with a USB over Ethernet solution and a J2534 device.
The subscription isn't even that expensive if you're doing it professionally. Certainly a better idea than faffing around with hacky shit.

Unlike in the very old cars, in all the newer cars regardless of make and model the "ignition" is turned on by the authorisation module.
If you don't have a matching key, then your immobilizer in the ECU doesn't matter because the ECU won't even get powered on. You literally can't turn on the ignition.

But you still need a precoded key. You either need to buy it from Audi or prepare yourself with the cars immodata, which is not easy for this type of immo, as mentioned before.