Hi Akma, welcome to the forum. You could try the following:
Check the product label ingredient list and compare to your country official list of allergens (e.g. milk, egg, nuts, peanuts, etc.) However, if the ingredients don't state their sub-ingredients you cannot be sure (e.g. chocolate may contain soy and milk, coconut strings may contain sulfites, cookies may contain wheat, etc.). So, your further action might be to request Allergen statement from the supplier. That's a normal practice - because you, as a distributor, are responsible for not only distributing products to your customers but supplying them with product information (e.g. specifications, GFSI, Letters of Guarantee, COO, etc.)
BTW, Certificate of Analysis would not help you as it doesn't usually state product ingredients, only chemical/micro/physical profile.