@sander @CannaSoftware Just out of curiosity: would glTF work instead of FBX? glTF supports scenes (hierarchy of objects), materials and mesh geometry.
I know for a fact that Blender can import it (although its import functionality doesn’t support compressed meshes/textures, but as far as I understand that’s not a problem for you). UE and Unity support glTF too I think, and Maya and the rest either have a glTF add-in or you can use Blender to convert .glTF to .fbx