Yep +1 for wanting this in an eye cyberware modification. As for gameplay I'd like it to auto-activate when scanning and the average light level in V's FOV is lower than some preset amount, representing "it's dark". I don't want a new/separate keybind for it.
I often instinctively switch to scanning mode in dark places, expecting to be able to see better and of course I don't (except for some interactive things being pointed out).
It would also make higher-capacity Kiroshis more important/useful. As things stand I barely ever have more than two eye mods active (threat detector & <I forget the name but the one which gives +crit chance>).