The following export options might be interesting:

• Embree scene format;
• OptiX scene format;
• OpenGL: setup all the buffers and shaders, and return a struct with information for the camera, scene graph, and ids of the buffers, textures, shaders;
• CUDA?
• OpenCL?
• Some other?

Maybe have a "plugin" approach for each, to avoid depending on CUDA, Embree and others, if one only wants to use the OpenGL export option, for example.