For it to be buoyant, density would have to be less than air. If we’re holding to conservation of mass, then the bottle would have to be significantly larger than the paladin, which doesn’t sound particularly stealthy.

If there are in a sealed container that wouldn’t matter, unless it flies using a magical force without an equal and opposite force, at which point you might as well just throw out conservation of mass.

One with roads coloured too would probably also be informative. And I feel like this could be scripted with openstreetmaps to make them for different cities and compare them…