Blow off valves are only meant for turbochargers so if you’re thinking of getting one for your supercharger, then don’t as it will be a waste of money.
A true supercharger works with forced induction and is designed to stay on and recognize pressure, so doesn’t need a blow off valve to sense a pressure build up and vent it off. However, some superchargers are centrifugal rather than using a combustion system and so a form of blow off valve can be used - but it will also need a mass-air meter installed otherwise a blow off valve will be pointless and can actually lead to performance issues in your car.