> unfortunately, WebXR restrictions make AR passthrough and the camera feed mutually exclusive

It looks like Chromium-based browsers might be doable?[1][2]

Meta: About a decade ago, I rolled my own WebXR-like stack with passthrough, and played with an XR Powers of Ten zoomer. Here we are years later, and it's apparently still not something which might be deployed. In some sense, we are progressing so sloooowly.

[1] https://caniuse.com/wf-webxr-camera [2] https://immersive-web.github.io/raw-camera-access/