Yeah, according to google a pair of raybans weighs 40 grams and a pair of xreal air weight twice as much at 79g. I'm a massive fan of the latter but already that weight is noticeable on your face as being heavier than a standard pair of glasses and this is a device which has no battery. All the power comes from a cable connected to whatever device you're using. I can wear a pair all day but I don't think you could go too much heavier before it starts getting uncomfortable for prolonged use. I think it's going to be a massive struggle to get these down to a decent weight with battery. Viture's solution to this is a neckband containing the battery and the brains - I could definitely see this kind of solution becoming commonplace.

https://xreal.com

https://www.viture.com/