I know of a company with a large fleet of pickup trucks that had placed an order for GMC trucks, four digit quantity, which GMC said the volume was too high for them to fill, by about 700 trucks. That company then went and bought the other 700 from Ford and that was a single year's order. That's the market and the reason why pickup trucks are the best selling vehicles. It's not individuals that are purchasing, it's companies with significant fleets and that's because there's this huge aftermarket for pickup trucks that involve modifying the truck, typically by removing the standard bed body and placing a different body with the cab and chassis and the trucks from each of the manufacturers are just different enough that those bodies are not universal to the truck.
You're probably right that the pickup truck is probably not what he's talking about. Tesla could trivially break into the consumer market for it but there's the huge support network build around Ford, GMC, Toyota, Chrysler, etc that Tesla simply doesn't have when it comes to aftermarket unless they engineer their vehicles to have the same fittings as, for example, a F150 and consequently can utilize Knapheid service bodies for the F150. When you get into larger trucks, where International is the big player, you'll find that the bodies are more custom in their approach, since International typically only builds a cab and chassis, so that's a bit easier for Tesla to break into.