Pickering... you can forget about that in europe. Nam doc mai, maybe. Canarius sold one clone of nam doc mai named "Mun" but to be honest, nobody has been able to clarify if it was a clone more adapt to be eaten fresh, or it was a dessert variety. However, they apparently taste good when ripened, so you should be able to grow a decent plant from them.
One last thing: i don't think that right now is the best moment for buying/planting a mango tree in Italy, even in Palermo. You've got to wait at least till spring.