The visionOS behavior follows the precedent set by Safari Voice Search for iOS/iPadOS, but it’s even more natural and fluid in that you don’t have to target a graphical element (i.e., a microphone button) before you can start speaking.
Siri also benefits from the superpower of gaze awareness, taking into account where you’re looking when you say commands like “add this to Up Next” or “share this with Tasha.”
My Siri contributions included multimedia mockups of realtime feedback in apps during active conversations with the assistant, as well as mockups, policy bullets and state diagrams covering invocation, listening, responding and dismissal behavior.