Ain't that the truth... the community for this car really went to shit when every 16 year old with a hard on could afford to buy one.  Most of those posers would be appalled at how ratty my car is.

Looks like the cars with that ECU fitted use narrow band sensors.

yes, and also you can check block 31 with vcds/vagcom.
if you have lambda values there (at idle 1.00), you have wide band, if volts are there, not..

Has been there any progress in this direction? Is there an easy way to convert 2.7T to Wideband? Considering this as a perspective platform for tuning after playing with 1.8T. The only one thing stops me - there is no known complete solution for Wideband.

Possible ways I see:
1) port Wideband handling from ME7.5 into ME7.1 via asm code injection, use second Lambda as an input for voltage, then translate that voltage into Lambda value and patch those places when ECU goes to open loop, instead use closed loop & input from second lambda.
 
2) Convert ME7.5 from 1.8 T, lot more changes will be required because of different engine volume, different count of cylinders, different hardware (modification of SY_ constants, lot more patches in asm code & wiring)