There is only one FAA rule that you need to be aware of for FPV headsets for your drone, that is the line-of-sight rule. When flying outdoors, you must be able to see your drone with your naked eye at all times. If your face is in a headset, you can't see your drone. I know you are seeing the world from the perspective of your drone, and in some cases that is even safer than viewing from the sidelines, but that's the law. To fly outdoors using a headset, you need an observer — a person standing by your side, acting as your eyes to watch the drone and inform you if anything goes wrong.