DSG? IIRC those needed trans fluid change every 40k? Might want to check on how to do that and/or price to do at a shop. Not sure how reliable the DSG's are today, they were kinda iffy at one point.
Diesel engine requires diesel oil--you probably know that but it has to be stated. I don't know what VW requires for this engine. For a while they required something kinda costly, err costly compared to run off the mill conventional. I'd be concerned about having the right oil used, but at 36k, that is pretty low miles. Pretty sure this is a timing belt motor, so take that into account. And it would be an interference motor.
Used to be, the recommendation going in was to know who your TDI guru was. Who was going to service it, and repair it, and to make sure you were on good terms with them. Maybe the dealership has stepped up their game but that place used to be the last place to go. Do you plan to fix it yourself, or farm out any repairs?
VAG-COM is the aftermarket software for reading codes; pricey but that was the go-to tool when I had mine 10, 15 years ago.
I'd check on mpg for this, then figure out cost per mile for fuel, then compare against what gassers do. I suspect they are much closer today than they used to be. I loved my diesel but from what I've read the turbo gassers have closed the gap. A VW though might have the edge in driver's comfort.