Overall I was told that you did not need to know everything about AWS and did not need to have a cert. However despite having a Solutions Architect cert, I was still quizzed on intricate knowledge of AWS tools. At the end of the day I had great rapport with the team but it seems like if one person woke up on the wrong side of the bed that day you're out of luck. In that way, these roles require good luck on your interview day. To be honest the leadership principle-obsessed answers feel corny at this stage. I miss the old days when all you needed was a great answer to a question.