Links
https://help.shopify.com/en/manual/sell-online/amazon-sales-channel/amazon-list-products#create-a-new-listing-for-a-product
-create listing on amazon
https://brandservices.amazon.com/
-create brand for amazon
https://help.shopify.com/en/manual/sell-online/amazon-sales-channel/amazon-list-products#add-your-registered-brand
-how to add a register brand and avoid gtin number requirements
1-888-280-4358
-amazon seller central