Sure, the Iron Cross with black, white and grey motif is German. The current German Armed Fores use it as their logo. But a similar cross, just with Polish colors could be readily adopted and used in conjunction with the Polish Military Eagle. The Eagle would be placed on the Hussar Cross.

The Military Cross theme is hardly German, though. Just look at the military logo of Ukraine, it's an Iron Cross theme. This all goes back to the Maltese Cross which was first used during the Crusades. Fire Departments in the United States even have a similar cross logo since the Cross is said to protect from fire and symbolize valor and courage.