I'm trying to extract the GoPro Hero 9's firmware to tweak some of the parameters. This is my first time doing any sort of reverse engineering but I'm hoping that by finding the filesystem I can update the constant and rebuild the firmware. Unfortunately, I haven't been able to identify the firmware's filesystem correctly. The firmware can be downloaded here: https://bit.ly/35JJlcc or here: https://community.gopro.com/t5/en/Introducing-GoPro-Labs/ta-p/603173 by clicking HERO9 Black at the bottom.
binwalk -e doesn't seem to result in any useful information, very similar to this post. Entropy analysis and browsing the hex dump seems to indicate the firmware isn't encrypted but I haven't been able to find any pointers to the underlying filesystem.
In the extracted
binwalk -e files I did notice that it seems to find a
romfs file, but I suspect this is a false positive based on the file size? I'm not sure where to go from here, would appreciate any tips to figure out the underlying fs.