Only dealerships in the VW Credit network (VW, Audi, etc.) will have a payoff similar to yours. That’s the best route to maximizing equity without paying TTL. Talk to multiple VW and Audi dealers to see what equity they’ll offer you. Also Autonation and Carshop (since they own dealerships) and the LH brokers listed in this thread.
VW Credit will charge “estimation of fair market value” to everyone else. So your equity basically evaporates going that route.