Hi Heimo, this is a great idea thanks for sharing!
You would be able to achieve this effect in Arkio if you applied a normal texture to this dome shape. (an UV mapped JPG or PNG image) Currently, the HDRI textures will not be exported as a default material from Blender and Arkio currently does not support importing HDRI textures so that is where information currently gets lost.
It’s also possible to UV map a half/full dome with a normal texture (JPG/PNG) to achieve a similar effect. The same strategy can be used to load other UV-mapped meshes to Arkio for eg loading photogrammetry scans of 3D surroundings or procedural textures that can be applied to the geometry as normal UV-mapped textures.
We will also look into HDRI textures but let us know if you found a good way to get your skybox textures to Arkio!