Something thats slightly less vulnerable (even if not completely immune to) flares, or flashlights, or even simply just less "grain", or any other number of things, but at the cost of aim-down-time or something else.
Was thinking in helmet/hat slot of character, thus also costing head armor for those that can get it.
This came about from a chat from a user complaining just how the NVG seem to be "Gen 1 night vision goggles" and how they have so much grain and are "so bad"
Maybe this could be extended to allow thermal-based or IR-based NVG or other types/gens, with their own downsides? Not sure, TBH not the most fleshed out idea, but want to give it and see where it goes