The page link field returns the URL. Yes, this is just like using get_permalink(). When selecting pages/posts. ACF stores an array of post IDs. In order to reverse query this you need to do a “LIKE” query.
$args = array(
'numberposts' => 1000,
'post_type' => 'product',
'meta_key' => 'page_link',
'meta_value' => '"'.$post->ID.'"'.
'meta_compare' => 'LIKE'
);