At one point I dismantled all my gimbal assembly to see if there was a way to physically correct the angle. There wasn’t anything that I could find to achieve that.
I know the gimbal recalibration has never achieved anything.
Curiously, I did replace my gimbal at one point (for a reason I can’t recall) … and I’m certain the offset was still there afterwards.
The only time it REALLY annoyed me was when I wanted to fly a circle around a POI … and I had to remember to set it up making an allowance.
This post is the video from when I first discovered the problem.