Another solution (if you don't want add an hardcoded ID in your code) is :
if (strpos($cms->meta_description, 'REDIRECT:') !== False) {
$this->_menu .= '<a href="'.str_replace("REDIRECT:", "", $cms->meta_description).'">'.$cms->meta_title.'</a>';
}
else {
$this->_menu .= '<a href="'.$links[0]['link'].'">'.$cms->meta_title.'</a>';
}
That allow you to set: "REDIRECT:/myblog" in meta description of a cms page...
So in your menu, you can add this cms page, which one will be just a link to a external page...
You can see here an example : https://www.perfecthealthsolutions.eu in the "Informations +" Menu
PS : I do it in meta_description, but you can do it in your favorite field.
But perso, I prefere to keep the $cms->content() with a simple link to allow a fallback if I update the module and forget to cherry pick this change !