If you have text on the page that already includes all of the information the image conveys, then your product image does not require alternative text. The image can be coded as decorative so assistive technology ignores it.
However, remember to consider the full context of the image — alternative text may improve user experience, even if it’s not technically required.
For example, if the image is part of a specific images section or widget, users on assistive technology may expect to find images there. Instead of marking these images as decorative, another option is to provide brief alternative text that also informs users where to find more information, such as “Large pet blanket, full description in product details.”
For support in locating and evaluating images on your product page, explore the Guided Manual WCAG Audit Tool from Accessible Web.