It seems like customers cannot update quantity of products at the checkout level - would it be possible to make this function feasible so that customers can easily update product quantity at checkout rather than returning back to previous steps? I don’t see an option for it in the admin settings or the theme settings. If so, how would I go about it (whether its code or via a setting)?
you can’t change products quantity on checkout page there is no option such things.
Four years later, and still awaiting this feature