I ran into the same issue not so long ago and at least for no_std I had to resort to using the async_trait crate. (The project is no_std but has alloc)
I can't recall the exact error so it might have been due to mixing async and non-async methods in the same trait. I would have to look at it again...
Also check out one of their pilots YouTube channel: MattFrom103
He's got full mission videos, shot from multiple cameras around the helo, with onboard comms and additional explanations.