Back when I started my career in web dev (1997) VRML browsers were a pretty hot topic. They were mostly browser plugins rather than stand-alone though. I still think this is a great idea despite nearly 30 years of them being proven not to be commercially viable.
I myself have wondered why VisionOS Safari wasn't more leaning into the idea that the DOM has semantics (e.g. <header> <footer> <nav>) and CSS is already able to convey depth information.