It looks like these cameras are infrared and intended to see gestures from the wearer. There are some more details in the linked article:

https://www.macrumors.com/2024/06/30/new-airpods-to-feature-...

> The IR cameras can detect environmental image changes, facilitating a broader range of gestures to improve user interaction. For example, if a user watches a video using Apple Vision Pro and the new AirPods, and turns their head to look in a specific direction, the sound source in that direction can be "emphasized to enhance the spatial audio/computing experience."

I wonder if the signal could be integrated into AR glasses or headset to provide a wider FOV to the wearer.