I was very curious about MAVLink over LoRa earlier this month and even bought a couple of modules for experimentation. I was encouraged by the mere existence of the Zoon module, though I admit I didn’t look closely at the product at the time (it appears to have been a failure). Their claim of full duplex communication with the weird parenthetical qualifier in the OP should’ve been a clue that there may have been a bit of snake oil sprinkled into the mix…
Through my own research and experimentation, I quickly discovered that LoRa is very ill-suited to MAVLink messaging. Some very simple math will show that even under ideal conditions at short range, LoRa bandwidth is insufficient for anything other than a very handicapped MAVLink connection. Any use of the truly great features of LoRa to increase the range further limits the bandwidth.
I had some pretty good success with ESP-Now, which is a 2.4GHz protocol developed by Espressif for their ESP8266 and ESP32 modules.
For a more robust solution, look toward SIK radios, RFD900 radios, DragonLink, etc.