How to get the camera capture photo event in Quest 3?

Cannot receive system button events for the right controller in Quest 3?
So it cannot be used as a judgment for photo events.

Are there other ways to determine the event of a photo being taken?

I’m not sure what you mean, there’s no built-in OpenXR functionality for screenshots. If you’re trying to control an application event, you can create a boolean action, suggest bindings for whichever buttons you want, and use that to decide when to trigger your event.