Cygolite is a great company that’s been around a long time, making super dependable and affordable lights.

They sell a Go Pro mount for their lights that’s $10 U.S.

So for about $50 U.S. you could be all set with a light and mount.

They sell the mount direct, link:
https://shop.cygolite.com/product.sc?productId=114&categoryId=94

They sell their lights through dealers, but even Amazon is a dealer.

Suggested light, link:
https://cygolite.com/product/metro-plus-650-usb/

edit: link to light at…
Cygolite’s Amazon Store
https://www.amazon.com/dp/B07544KPJL/ref=cm_sw_r_sms_api_glt_fabc_GSC47BV7YR5BQ7RQJEKE?_encoding=UTF8&psc=1