As I understand it, one cannot check in online and receive their boarding pass if using a new passport. The new passport needs to be swiped at check in at the airport.
If this is correct, can one go to the airport prior to the day departure and have this new passport added to the profile/PNR?
not correct for about the last 2 years.
When checking in in with a new passport, you’ll have the option to take a picture of the page with your picture, it will read the ‘code’ on the bottom of the passport, send through to some service to verify, and you should be able to check in fine. YMMV though, I’ve had to read easily sometimes and take several tries others. It also can take a few minutes to verify. But it normally works.
It wont complete check in for countries where’s visa is required, but IiRC, for some, it can also scan visas. There’s another thread somewhere on it - I think results have been mixed.