The good thing about the BAD engine is that its mechanical basics are good and robust. As far as I know there are quite some here in the forum that have done over 200.000 km that are still running fine. I would not be too worried about block, pistons, crankshaft, valves, camshafts etc. as they generally run very long (different to many of the 1.4 AUA/BBY). I know of no BAD with oil consumption (different to many of the 1.4 AUA/BBY).
The typical BAD problems are in the periphery, as already indicated. Especially fuel injection (injectors, HP pumps), ignition (coils), cooling (elevated temperature as standard under part load, with plastic parts), air intake (swirl flaps) and exhaust (NOx catalyst) are known frequent issues. Make sure these are addressed timely and I bet it can serve you for a long, long time.
An ADAC/DEKRA check might give you comfort. But I doubt whether it will address any of these typical FSI pains, I think they will address the typical TÜV issues (wear and tear, brakes/tires/shocks/exhaust/corrosion). You might better look, like you are doing, for a good mechanic and/or a meeting of A2 enthousiasts. How about https://a2-freun.de/forum/forums/forum/30-ost/ for meetings or