I don't think giving metal helmets night-vision capability would be particularly gamebreaking, it would make them more vulnerable to EMPs while letting tin can spearman not miss most of their spear throws while in caves
It might be too strong for tincan AR but they're most likely going to be running seeker lenses anyway
Grey Army Spec Ops helmet exists but that would have worse mech defenses since no padding and more options is a good thing
