Connecting two Waymo geos with a train would be an interesting company idea. You could lease freight track the way Amtrak already does it in the American West but try to negotiate a contact more favorable than Amtrak's. You could try to work with Waymo to work on bundles.

Amtrak could do the same thing but because of how Amtrak is organized in not sure that it would be possible. Most of the current Waymo geos are not connected by Amtrak directly and require transfers.