When DJI released updated firmware for their DJI FPV system with improved OSD, Betaflight users started cheering. The move to add OSD with elements like GPS position, the artificial horizon, etc is kind of puzzling. It works only with Betaflight flight controllers and a typical user of Betaflight does not really need it. After all, Betaflight concentrates on racing and freestyle on 5-inch mini-quads, not long-range.
On the other hand, users INAV, that concentrate on airplanes and long-range flights, can not use new DJI FPV OSD. Pilots immediately started to ask INAV developers to implement DJI FPV support. The problem is, that it's not working like that.
- Support for Betaflight is built-in into DJI Air Unit, not another way around.
- DJI FPV seems to be actively checking if the flight controller it talks to is Betaflight or not
INAV and Betaflight support the same serial protocol: MSP. This means DJI FPV is capable of talking to INAV, it just refuses to do so
- INAV and Betaflight use the same OSD positioning protocol using the same MSP frames. Still, DJI FPV refuses to talk to INAV
- We have no idea what DJI Air Unit expects from a flight controller since it is the closed source!
All of that means that INAV developers can not fix something that is not within the code of INAV. For INAV support, DJI has to implement it. Not the other way around.