I made an app.
https://play.google.com/store/apps/details?id=ch.pocketpc.nearbyglasses
Nearby Glasses is here to warn you when smart glasses are nearby.

I hope it's useful for someone.

The app is open source, free and rather simple
https://github.com/yjeanrenaud/yj_nearbyglasses

It's also downloadable outside the Play Store. iOS port is in the making