I've tried helmet mount and glasses mount, could never get them aligned right and if I did I soon broke them or knocked them out of alignment. But many have success with them.

I settled on Sprintech bar end mirrors that you can get on Amazon for under $20. Glancing down works fine, they last a long time, easy to adjust. and don't really stick out - I'm not breaking them (I have them on 2 bikes).

None of these come even close to what you are used to in a car and none of them replace the need to still look before you move/turn left, but definitely a safety increase.