I loaded a plane firmware, boot into it, then power-off, go into dfu mode, perform a whole chip erase with Stm32CudeProgrammer.
Then I installed copter firmware and load my parameters.
I still got High GPS HDOP warnings.
I found this:
Copter: GPS arming check fails when no GPS present despite good position from visual odometry · Issue #14661 · ArduPilot/ardupilot (github.com)
That warning seem to be a expected behavior as this issue is still open (so I assume it is still valid).
I disabled arm check for GPS and now it will arm and takeoff in Loiter and Guided.
Will arrange a real flight to give the current config a try some days later, and update this post.
Might still have problem (or not) as lat&lng in AHRS2 still pin at 0 and won’t change. I am not sure if this is expected.
Thanks a lot for your attention.