The emails I was getting all summer seemed to suggest they were trying to direct as many people as possible to interviewing on arrival. I was able to eventually get a local appointment, but my guess is that as long as you arrive at an airport doing interviews on arrival during a time they are open, you'd be able to do it.

No idea what wait times are like - my renewal process sitting with the officer to do fingerprints took less than 5 minutes. It *could* be a really quick thing, but I know it could be a concern if you're looking to make a connecting flight.