Babylon.js Viewer: Babylon.js Viewer | Babylon.js Documentation
The Viewer uses WebVR system in BJS. Sadly WebVR has been deprecated and no longer works on current browsers.
Also the VR button doesn’t do anything when you press it because browsers no longer support it.
You can opt-in to WebXR via WebVR with the following:
However it’s not the recommended approach in the BJS docs.
Is using WebXR in the Viewer on the roadmap?