It was a weather/surveillance balloon. They aren't mutually exclusive. China works spying into everything they do. Of course so does the US. Nobody except the people that launched it actually know what capabilities it had. Everything else is speculation. The debris landed in shallow water so the FBI will probably learn a lot more about it.
Ok, smart guy/ comic relief.
It was shot 6 miles off the coast of South Carolina. What is the exact depth of the water there?