Bring it DOM!
(Somebody please help us with better pun's) ;]
Delivering HTML-like experiences in WebXR is quite a jump back in time.
No CSS, No DOM, basically no GUI / styling standards, like game-development.
A hybrid approach, would be interesting to combine the best of both worlds:
As you can see, as soon as things get smartphone/standalone stereoscopic, the CSS/DOM-possibilities dissappear.
For stereoscopic experiences, SearXR emulates a (stripped-down version of) DOM in WebXR.
Just take a look at SEARXR, and see how this hybrid mix can work on various devices.
NOTE: Big respect to all VRML research, which has directly and indirectly paved the way for many DOM-like tools & technology (also AFRAME, react-three-fiber ).