Amazon is ready to hit the road across the U.S. with the first of its custom-made Rivian electric delivery vans, and a lot may be riding on it for both companies. Rivian CEO and founder R.J. Scaringe and top Amazon executives were on hand Thursday afternoon to unveil the electric vans at an Amazon delivery station in the Pullman neighborhood on Chicago’s South Side, where packages will be loaded for delivery to doorsteps. “We’re going to be putting a lot more of these on the road,” said Scaringe, perched in the driver’s seat of a road-ready EDV 700 electric van. “And we’re going to start seein…