I would probably wait a little bit to buy a Rivian.
They are focusing on not having to raise more funding, trying to scale new production facilities, and start their own private DCFC network. The Rivian forums give the impression that the vehicles have a variety of recurring issues.
I waited several years to buy a Tesla due to some of their earlier issues. I think it is fair to say every brand will have their own unique issues that plague the earlier models. Lastly, the DCFC isn’t where it needs to be. Rivian are thirsty, so those owners will become quite familiar with these stations.