Move “Menus” link from Appearance > Menus to its own tab on left column Dashboard

Here code how to add new menu and remove old

add_action('admin_menu', 'change_menus_position');
function change_menus_position() {

    // Remove old menu
    remove_submenu_page( 'themes.php', 'nav-menus.php' );

    //Add new menu page
     add_menu_page(
       'Menus',
       'Menus',
       'edit_theme_options',
       'nav-menus.php',
       '',
       'dashicons-list-view',
       68
    );
}

after this can be some bug with opened “Appearance” but you can fix it with css

you can dump all menu

global $menu,$submenu;

echo '<pre>';
print_r($menu);
print_r($submenu);
echo '</pre>';

wp_die();

---

Also it’s possible add custom separator (space between menus)

function add_admin_menu_separator( $position ) {

    global $menu;

    $menu[ $position ] = array(
        0   =>  '',
        1   =>  'read',
        2   =>  'separator' . $position,
        3   =>  '',
        4   =>  'wp-menu-separator'
    );

}

and use

add_admin_menu_separator('21');
add_admin_menu_separator({custom_position});