On the Canadian credit application for an Amex card after it asks for your full name it asks next: how do you want your name to appear on the card? I don't remember Visa asking this. Does this mean we can choose a nickname of our choice? It does say the FULL last name must appear though.
It's for a preferred name. For example, my given name is 'Daniel' but I prefer to be called 'Dan'.
Your first name on a debit/credit card isn't important which is why they ask you for your actual surname... but that doesn't mean you're allowed to make up a first name like Superman, unfortunately.