Take a look at this video, around 2:14. The gentleman playing describes it as the world's only existing soprano rothphone. Based on the sound, I think it's a Saxoboe (sorry for a Pinterest link, but I wanted to show the whole horn). Opinions?
It could simply be a attempt at a metal oboe and nothing more. The issue is that if this is the only "soprano rothophone" it would be very hard to prove it. The key layout also confuses me is it a weird combo of sax and clarinet keys or maybe uses a system similar to Albert system clarinets?
The Saxoboe I linked to, above, looks like it has all the standard keywork for a normal saxophone, minus a front altissimo F. You could get saxophones, particularly on the low end (bass, contrabass), without a front altissimo F until after WWII, so no biggie, there. The picture I liked to doesn't show the low left hand G#/C#/B/Bb very well. Here's a better picture.Here's a really good picture of the left hand pinky keys on an Albert System clarinet.