You might want to look into headlamps. They're right angle flashlights that strap to your head, so the light will always shine where your face is pointing. Attaching any kind of mass to my glasses doesn't sound very pleasant.

Since this is a flashlight community, take a look at this: https://intl-outdoor.com/emisar-dw4-right-angle-1-18650-work-light.html

You'll be able to find to tons of options at your local hardware store too. The thing to look out for is CRI. Basically, the higher the CRI the better you'll be able to see a wide gauntlet of colors.

Parametrek runs an awesome site for flashlight selections. http://flashlights.parametrek.com/index.html. They’re super knowledgeable and I have found it to be an invaluable resource for identifying options based on your selected parameters. I agree high CRI, rechargeable headlamp is a great option. Rechargeable means you don’t need to worry about specialty batteries and chargers which accompany many of the higher quality enthusiast flashlights available. It might still have a different battery than you’re used to but you can charge it in situ.

FWIW if you do want to just rubber band something to your glasses wing, there is a Lumintop IYP365 (In Your Pocket 365 days a year) it has a high CRI Nichia LED option which is great quality and runs on standard batteries - Eneloop rechargeables are a great option. I read feedback from people who use it as an inspection light in the aircraft industry and their feedback on the colour quality of the light sold me. It’s like a medical quality pocket light where the way colours appear while under illumination is obviously critical - just doesn’t have the M.D. price tag.

Something like this?

https://a.aliexpress.com/_mMi5OWq