I only had my allroad a litte over a week ago, bit the bullet and purchased a genuine unit from https://www.gendan.co.uk uk supplier Ross-tech and only a hour or so away from me.
I already had a carista dongle I picked up years ago for my other vehicles which I used to check the car before purchasing...
It has error checking functionality and some modification options but not nearly as much as the VAGCOM has, but only around £35 on Amazon, if your interested in this see https://caristaapp.com/en/supported-cars for what it can do on the A6.
I was after something that could complete towbar coding and know the value of having additional access to the systems after using a IID tool for years with my departed Discovery.