May one interject and point everyone in the direction of practicality and pragmatism. Instead of searching around for a rule or regulation which in my experience leads people down the path of poor airmanship and a more stressful life just use judgement and common sense.
NVG are an aid to visual flight. Generally helpful in conditions of VMC and acceptable light levels. If you can make out features on the ground use them. If you’re IMC and can’t see anything, don’t use them.
Let’s not get wrapped around the axle about something that’s quite straight forward.
LZ