Bake LightDirection for Lightmaps?

Last days I tried to bake lightmaps with cycles, thanks to the IntelOpenDenoise we can do perfect 4k lightmaps in seconds (same with the rest of bakes works)

I have tried to make a lightmap in blender but I cant find a way to bake the directional lightmap. I have tried with nodes but we don’t have any way to access to light direction. Like I have seen is a common problem and don’t appear to have solution from user pov (a lot of people needed this for some effects)

The directional lightmap is a texture that contain the light direction (an interpolation between all the lights depending of the power of each light), it is necessary for realtime, and with this texture and the normal map the engine can show how the light is affected by the normal map.

More info

-Am I right? It is not possible?
-This is a limitation of cycles paradigm or only is not implemented?
-Could be implemented in some future? or it is out of any roadmap?