"xrOS" is visible on the simulator title bar in the platforms state of the union. Just didn't get picked by marketing ultimately. I'm glad; "XR" as a term sounds too overly techy. The marketing is bringing this futuristic thing down to earth, making it relatable.

xrOS was likely one contender for the project until Marketing and execs came together on the final names. They chose a few and trademarked a number of them: https://9to5mac.com/2023/05/23/reality-pro-os/#:~:text=As%20...