I just got my cover from Interrobang automotive about 3 weeks ago. Very nice and uses the rivian channels. So, it doesn't stick up above the bed. That's another option for you to consider.
That works for a big company like Apple and the volumes that they sell. Rivian is a new company that isn't selling that many vehicles. Rivian doesn't have the clout to negotiate great prices like Apple does. I'm sure motor manufacturers are trying to sign contracts with GM, Ford, Toyota, & VW.