The latest RS6 Avant has been released in NA, the previous generation was not available
They only have the RS6 Avant and the A4 and A4 All-Road in NA, and getting them is easier said then done. They also have their e-tron which is wagonish.
I drove one of the e-tron’s as a loaner while my car was being serviced. It felt heavy, and slow, but didn’t offer anything like the amount of space I’d expect from a wagon. More like a hatchback.