I think most handheld navigation aids infer direction of travel from position information. An electronic compass gives the orientation of the device, who knows how it is being held.

I guess they use a compass when it's available, like for trying to display a map oriented to compass north, but I don't think it is dependable as algorithmic input.

Something mounted in a vehicle can directly factor the compass data into directions though (just saying that to emphasize that I'm talking about handheld stuff above).