I fail to see what the big deal is about Global's tie up eith Amex which Global claims is huge News with numerous Instagram reels. So they have agreed that you will be able buy stuff they sell with Amex and there seems to be a discount/perk. Amex is not widely accepted in comparison with Visa or Mastercard and any merchant can agree to accept Amex if they are prepared to pay the higher fees. Considering Global does not offer a product (other than polyester hoodies) I fail to see why they are even mentioning that Anex has agreed to let them accept Amex for payment and that it may offer a discount to card members in the future. I tend to use Amex and I would expect any airline to accept Amex as standard.
At the moment they only accept Google pay and Shop pay which do not work in a number of countries. Hardly Global!