I’m not so sure about that. Interstate trade is the sole domain of the federal government technically. If you are in Tennessee buying from a manufacturer in Detroit, I would think that federal laws would override state laws. Realistically, I’m not so sure how that works okay out.
I think part of what Tesla failed at was opening direct buy dealerships in states, which becomes Intrastate commerce. They do allow you to direct buy, just not from the “showroom”.