Will a supercharger fit on 2005 Saturn Ion sedan?

No, a readily available, bolt-on supercharger kit is not available for the 2005 Saturn Ion sedan. While you *might* be able to custom fabricate something, it would be a very significant and expensive undertaking, likely exceeding the value of the car. The Saturn Ion's engine simply wasn't designed for supercharging, and there's no established aftermarket support for it.