Got AZ as a walk-in at a local pharmacy today, one of two walk-ins they were able to do this morning - the rest were all appointments.
I was there when they opened and asked; had to be there anyways, so it wasn't a special trip.
One note: I was talking with one gentleman while we were both waiting afterward; he had an appointment for Pfizer for next week that he is now going to cancel since he got AZ today. If you are in a similar position and have multiple appointments -- cancel the one(s) you don't need instead of being a "no show", so they can allocate that vaccine dose to someone else in advance!