Image optimisation advice assumes you are writing alt text for a page. On an ecommerce catalogue it is a data problem, and the manual approach does not survive contact with the volume.
Generate from structured data you already have
Product name, colour, angle and material usually exist as fields. A template assembling them produces accurate, specific alt text at scale — considerably better than the empty attributes or filename-derived text most catalogues carry.
Accessibility is the actual obligation
Alt text exists so screen reader users can use the site, and in many jurisdictions that is a legal requirement rather than an optimisation. Framing the project as accessibility compliance also unlocks budget that "image SEO" does not.
Decorative images should have empty alt attributes
Not missing — empty. A decorative image with descriptive alt text makes the page worse for screen reader users by announcing something meaningless. Getting this distinction right matters more than keyword placement.
Where the real performance win is
For most catalogues, file size and format do far more for Core Web Vitals than alt text does for rankings. If the choice is one project, compress and serve modern formats first, then describe the images second.