Wordpress Routes to make a Sitemap

base.php

<?php
/* paste at the top of base.php */

global $wp_query;
if(isset($wp_query->query_vars['sitemap'])){


  $blogs=get_blogs_urls();
  

  $menu = wp_get_nav_menu_items('Menu Principal');
  $sm='';
  $sm.="<?xml version=\"1.0\" encoding=\"UTF-8\"?>"."\n";
  $sm.='<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">'."\n";
  foreach ($menu as $menuItem) {
    // pa($menuItem);

    
      $sm.="<url>\n<loc>".$menuItem->url.'</loc></url>';
      
    
  }
  if(!empty($blogs)){
          foreach ($blogs as $url) {
            $sm.="<url>\n<loc>".$url.'</loc></url>';
          }
        }#pdf
  $sm.='</urlset>';
  // pa($menu);

 header('Content-type: application/xml');
  echo $sm;
  die();
}

mica.php

<?php 
/**
 * Add some rewrite rules */
function sitemap_rewrites_init(){
    add_rewrite_rule(
        'sitemap/?',
        'index.php?sitemap=true',
        'top' );
}

add_filter( 'query_vars', 'sitemap_query_vars' );

function sitemap_query_vars( $query_vars ){
    $query_vars[] = 'sitemap';
    return $query_vars;
}