and the pressure is the result of density.
so density is the true reason for buoyancy.
Pressure is the result of a force applied. That's the very definition.
Force (in our case) is not the result of density.
You can have a stone (hight density) side by side to some piece of wood (low density) there won't by any force pressing the wood against the stone.
The force (in our case) is the result of mass and gravity.
In a Zero-G-Environment you won't have this force, so you won't have pressure and you won't have buoyancy.
That's independent of any density differences.
But still there is a connection between density and buoyancy.
It just isn't "the true reason for buoyancy".
This is an applet simulation a submarine, showing the air-pressure, water-pressure and weight along with the resulting force.http://www.didaktik.physik.uni-muenchen.de/materialien/inhalt_materialien/auftrieb/auftrieb.zip