The featured image and the product title (the_permalinks) will now link to the External product URL that is set in the WooCommerce Product.

link_external_product_image.php

add_filter( 'post_type_link', 'wphd_wc_link_permalink_external', 10, 2 );
function wphd_wc_link_permalink_external( $url ) 
{
	global $product;
	
	if (!empty($product->product_url)){
		
		$url_external = $product->product_url;	
		return $url_external;

	}else{
		return $url;
	}

}

/**
 * Opens ALL external links in new tabs
 */
add_action( 'wp_footer', 'wphd_wc_link_permalink_external_script' );
function wphd_wc_link_permalink_external_script(){
  ?>
   <script type="text/javascript">
        //<![CDATA[
        jQuery(document).ready(function($) {
            $('a').each(function() {
                var a = new RegExp('/' + window.location.host + '/');
                if(!a.test(this.href)) {
                    $(this).click(function(event) {
                        event.preventDefault();
                        event.stopPropagation();
                        window.open(this.href, '_blank');
                    });
                }
            });
        });
        //]]>
    </script>
  <?php
}