Do they fill deodorant with freon?

No, usually, the deoderant composition is a solution in some liquid, then the cannister is pressurised with some hydrocarbon gas. Some of this gas dissolves in the liquid, some remains as a gas in the space above the liquid. When you press the spray, the pressure of the gas pushes the liquid out of the nozzel. Some of the dissolved gas come out of solution and maintains the pressure.