Basically, the idea is to create a complex scene in UE4 and render out stereo cubemap that can be used as stereo sky sphere and reflections in another scene. Is it something that can be done ? How?
Thanks.
You can’t render cubemaps in game and there aren’t nothing like IBL probes.
But you can do something like this: https://www.youtube.com/watch?v=cHzt73Tn0L4
*You can capture the scene with a sphere capture to a texture 2d, but then no idea how you can use that.
Well, render out cubemap is literally rendering a 360 deg. stereo panoramic image and saving into .TGA file 
Just as if it was a 3D app and not UE4.
That video is entirely something else, but pretty cool - can be used for time of the day or day/night or weather changing cycles.
Okay then to get 360º for sure you need the 1.6 - Scene Capture Cube | Unreal Engine Documentation but not sure how to use, you can get a 360º Image where you place and is stored in the set texture, then probably you can export etc.
Sounds like it creates dynamic reflection on any kind of object. It would work for mono panoramic image, but won’t work for stereo panorama.
Stereo panorama is captured with 2 rotating cameras, 1 deg. horizontal fov and 180 deg. vertical fov. each cam will capture 360 images that then need to be stitched. That’s the gist of it.