Current progress (not working...) is at zrgravity/cgo3-python
Probably my CRC is incorrect, or the initialization isn't happening fast enough. If you have some signal captures for the init sequence and some good commands with correct CRC, that could be really helpful.
At some point I plan on looking into if the camera can be commanded to start/stop recording over the serial interface with the gimbal.
The info I have about Mavlink I got from here:
I don't remember for sure, but I believe the checksum.h file I used was the same one from this library:
GitHub - mavlink/c_library_v2: Official reference C / C++ library for the v2 protocol
Official reference C / C++ library for the v2 protocol - mavlink/c_library_v2
All the signal captures I did are here in the .csv files:
TyphoonH_CGO3_Serial_capture - Google Drive

I keep meaning to look at this more, but just haven't taken the time.