Good news. The biggest spherical panorama hosting site, 360cities.net, is now supporting stereo panoramas.
All you have to do is package your equirectangular stereo pair as a square jpeg image, with the left eye view above and the right eye view below, upload it, document and publish, just like a normal 2D panorama. It will be recognized, tagged, and advertised as stereoscopic. In VR modes — invoked by clicking/tapping the ‘cardboard’ icon — it will be shown as a stereo pair. Otherwise the left eye view will be shown as a regular panorama. VR mode is available even on desktop, which is quite good if you have a mirror stereoscope.
More good news: 360 Cities VR display offers static pan, and even zoom. Static pan supplements the gyro-controlled pan, letting you change the “straight ahead” direction without having to turn your body. I love that. The VR zoom is based off a fixed resolution image, but the range is decent – maybe 3:1 – and it really helps you better appreciate many images. These features are most useful if you have a smartphone viewer that gives good access to the screen, like the Goggle Tech or Wearality Sky. Then you can pan by swiping a finger left/right, and zoom by pinching. Nice!