Shopify Supplier Product Upload

My Shopify store is set up and now needs four new suppliers added, each in its own dedicated collection so shoppers can browse strictly by supplier. I already hold the full product information, but it is only available for copy-paste rather than in a tidy CSV. That means every item—title, description, price, SKU, variant, image and inventory count—has to be brought in manually (or with your preferred import trick) and then assigned to the correct supplier collection.