Interesting. Can you place a marker on a map, for example directly south, so it points in that direction?
From the description, I couldn't tell. However I did see this note: "Only on iPhone, enabling the magnetometer allows the arrow to point in the correct direction when standing still."
I did see this "On Apple Watch, it also supports a compass mode that will point you towards north, using the Apple Watch (Series 2 or above) GPS functionality."