I recall these stereo views photos at my aunt's house as a child... not porn... bet when she died they were just dumped as trash.. tragic. There should be, and perhaps is, a national registry for work like yours, you are preserving a national treasure.
I looked up viewers since I have an attachment for my cell phone that will take stereo. Reading gave me an education on viewers. "Universal 3D Mini Photograph Stereo Vision Camera Lens For Smart Phone $10" Amazon. https://en.wikipedia.org/wiki/Stereoscope
I had the opportunity to restore one for a friend a few months ago. Her Mom had passed away and I was presented with many old photos, slides & negatives. Always learning. Thanks for sharing.