Here are some items we've found relavent to the study of your new GoPro HERO5.
Here is our teardown post https://gethypoxic.com/blogs/technical/gopro-hero5-tear-down-and-software-study
Also keep an eye on https://gopro.com/help/articles/block/Open-Source-Software since they haven't posted the open source software in clear violation of GPL and other licensing.