Yes, there are plans for a dash cam function. It will be designed primarily to serve the Rivian insurance service, but there will likely be some way for owners to access the images.
So far, they've only shown Gear Guard (aka Sentry mode). Would be good to have recording while driving (aka TeslaCam). VERY helpful when you've been hit! I caught something "interesting" when I was hit from behind in my Tesla Model S!!!