I had to buy one of the rare covers fot my mobile exact for that reason.
Without use of the magnetic sensor one looses the possibility to see the
the direction when one is not moving (fast enough)
For physical reasons there is no way around removing all magnets nearby.
So, if you want to see where
I found turning off the magnetic sensor in Osmand maps to cure the issue
with the magnet interrupting the compass of Osmand maps. It seems to work
now with the, use magnetic sensor turned off in settings for Osmand maps.
The car mount for my phone uses a strong magnetic and I found this to