I am just sticking this here as I think it really deserves more eyeballs. Olli has made amazing progress in integrating Mavlink into OpenTX. Sadly his PR has not received much attention (I think) from OpenTx devs as I guess a Mavlink GCS is a niche for hobby use.
I achieved much success with full GoPro Hero 7 control with mavlink using a Storm32 and ESP32 and look forward to finding time soon to pick this up. Project page is here:
https://www.rcgroups.com/forums/showthread.php?3532969-MAVLink-for-OpenTx-and-Telemetry-Script