Hi,
Currently, the engine supports exporting a model as a glTF. It does not support exporting the whole scene as a glTF. However, it would not be difficult to create an editor extension that creates a temporary model, parents every entity in the scene to that model, and then saves that model as a glTF. I will give it a try now. Keep in mind that terrain and foliage cannot easily be exported to glTF.
The color scheme is not currently user-editable, but if people want it would be easy for me to add a color scheme file the editor can load at startup.