Would it be possible given a traditional 360/180 degree panorama to show it with cesiumjs ?
There’s no one-liner to do this out of the box; but all of the tools you would need are already implemented. I’m not an expert but I think what you need is to create an EllipsoidGeometry and then use a cubemap material to texture it. There’s a somewhat useful example in the cesium materials pack: https://github.com/AnalyticalGraphicsInc/cesium-materials-pack/blob/master/Example/index.html that uses a checkerboard image for all sides of the cubemap.
Here’s the live demo of the above code: http://analyticalgraphicsinc.github.io/cesium-materials-pack/Example/
Would it be possible to instruct the camera to see the globe form the inside? then I think that would answer the question, then its just to put the panorama image on the globe 
Putting the camera at the center of the globe won’t work, but putting it at the center of a Ellipsoid geometry should.
Cool. I might experiment alittle with that.