Pair programming sounds so stressful and unproductive to me. You can't read someone's mind. Any interjections while someone is in the middle of coding can't be more than distracting noise most of the time. And I would constantly feel self conscious that I'm taking too long to write something, googling or asking Copilot stupid questions, etc. Reviewing after the programmer believes it's ready to review makes much more sense to me. Though Copilot can be very helpful as an artificial pair programmer.