Contacted by recruiter thought LinkedIn, phone screen with the requiter and another with the hiring manager. Brought on-site for a half(+) day interview with a few engineers, hiring manager and the requiter. They asked for a technical presentation to open the interview that should last 30-60min, during which most of the audience worked on their phones and paid little attention, then I was cut off and didn't even have a chance to finish a presentation that I worked on for over a week. However, after that disappointing start, the team of people I meet and the company were awesome (at least from the outside looking in). They have a very refreshing view of the workplace and the employer employee relationship, very rare for silicon valley. Learning about what they were doing and the culture in which they were trying to establish was the best part of the interview, easily. Although Rivian claims to only hire the Top5% of talent, this is highly questionable, don't get discouraged if you are not made an offer.

There is an initial call with a recruiter. If a hiring manager is interested, then you will have a call with one or two people in the section of the company you would be working with.