Now, that's something where I would consider dusting off the old VR headset if it had such a mode.
For Chrome on Windows, I had to enable "WebXR Incubations" (chrome://flags/#webxr-incubations), manually start Steam VR, then restart Chrome. The option to enable VR appears, but then in the headset it's just a white screen. Maybe I'm missing a step or maybe it's just broken.