how can I change the read more link destinations and direct all to the same page?

You could use the post_link filter to rewrite the permalinks for those selected products.

function redirect_products( $url, $post ) {

    if ( in_array($post->ID, array(1,2,3,4) ) { //1,2,3,4 = your product IDs
        $url = get_permalink(123); //the ID of the redirect page 
    }
    return $url;
}
add_filter( 'post_link', 'redirect_products', 10, 2 );