On-screen keyboard toggle hotkey - How does it work

I am using this on Android but I don’t know if that matters for this question. I noticed for the first time the On-screen keyboard toggle in the hotkey binds. It sounds like just the think I would like to swap between the on screen gamepad and keyboard for those emulated computer systems that you can swap between (i.e. amiga, commodore, PC-98, etc…) I just don’t see how it works. As of right now with the overlay set to retropad using the hotkey just seems to toggle off the gamepad not enable a keyboard overlay. Is there a way to set the keyboard overlay? Or is the better question is there a way to enable a hotkey to swap between two different overlays?