Sorry, I misunderstood. I agree that it could be risky. I've seen the claims that the rapid naat is a pcr and would work for the 72 hours but we wasn't willing to risk it. If all else fails, several in our group made appointments with a mobile testing service in Seattle that came to them but it was a bit pricey.
As for the ArriveCan, I only showed the qr code at the port on my phone. I did however print our the receipt from them and did a screenshot of the code as a backup. There was so much involved plus the uncertainty with it being the first cruise, I was paranoid.