DS did exchange to USMA -- he was NOT at top of class, though was in top 20%. It was competitive to get, required an application and I think an interview with some USAFA leadership. He talked with his advisor the spring of his C4C year and asked what he needed to do to be competitive and to make sure his academic schedule aligned with USMA (he was Mech Engr major) -- they planned out his courses for the coming semesters to make sure he met all his requirements with what USAFA needed and USMA offered. If he'd been an Aero major I don't think he could have gone to USMA on exchange -- academic courses need to apply to requirements.
He had a good time and made some good friends. He trained with USMA Triathlon team while he was there.
He only wanted USMA for exchange as his grandfather is a USMA grad.
He went in the Spring of C2C year. and was able to interview by phone for key Squadron positions for the following C1C fall (Zoom wasn't a thing in 2012)
Biggest glitch came when his last USMA Final was on the day of his USAFA Ring Dance and USMA would not let him take the exam early. However, they would allow him to take it at USAFA, proctored by a USAFA professor, but it had to be at the exact time of his USMA final - 0730 ET. He managed to find a prof who would come in at 0530 MT to administer the final to him. Because he had no exams the day before that last final, he checked out of USMA after that 2nd to last final, drove home (got home at 1am), flew to USAFA the next day (the off day), took his final at 0530 MT, and then went to his Ring Dance that night.
I imagine the process to get and exchange slot to attend USNA is similar