I have a BMW and I'm using iBusRR to get them to work.
My friend however has a VW and I would die for having the same functionality as I have. Only problem is, he doesn't have a multifunction steering wheel yet so I can't measure things for you. He is willing to buy one however if I can guarantee him I can make it work. He would be willing to pay 25$ for it without hasitation. I'm sure of that.
So if it's coming available for VW you have an interested party here!