You're not seeing much in search results because folks simply aren't using GoPro form factor cameras. They're large, expensive (unless you buy a cheap Chinese knock off), and cannot be easily mounted in smaller rockets. IF/when folks are using them, they're usually mounting them inside an ebay that has them facing outward, not up/down. The only commercial mounting that I've seen for GoPro form factors is here:
https://www.fusionrocket.biz/store-2/?model_number=CAM3
808/mobius keychain type cameras have been the defacto standard for quite some time because of their small size, minimal impact on aerodynamics, and adaptability with some tape to just about any size rocket, to include mach/mile flights (with the right tape or proper shroud). Essentially anything that has a shroud listed here:
https://www.additiveaerospace.com/collections/video-camera-shrouds is what most folks are using. Personally, I use a RunCam2 4K with flawless results.