Rivian has actually split out the software side to a joint venture with Volkswagen Group (the group independent of the car company which the group owns with others like Audi and Porsche). I think the goal is to have a platform other brands can license

This is the move that will win. Once available at that level, it will get adopted into smaller vehicles. There would be a huge market for self-driving golf carts or similar size vehicles in gated and retirement communities.