I've been using my Light & Motion lights and just had to buy their $10 GoPro adapter they make.

https://lightandmotion.com/collections/vis

Their adapter for those lights: https://lightandmotion.com/collections/bike-accessories/products/gopro-mount-urban-vya or Amazon https://www.amazon.com/gp/product/B00YIPFELI/ref=ppx_yo_dt_b_search_asin_title

​

Solid lights, but occasionally have part of their mount snap off after YEARS of use. Superglue fixed it.

I use these: Light & Motion GoPro Mount and Light & Motion Urban 350

Don't ride much in the dark these days, but that's the set up I used when I did. Would've preferred a Cygolite as I was very happy with their headlights, but only Light & Motion offered a GoPro mount at the time. Glad to see Cygolite has one now too.

Garmin Varia and a Cygolite HotRod for the rear lights.