Admin notices (avisos panel administración)

admin_notice.php

<?php
/**
* Some example snippets for the control of notices in WordPress admin panel
*
* @package 		PCianes\AdminUtilities
* @since 		1.0.0
* @author 		PCianes
* @license 		GNU General Public License 2.0+
*/
namespace PCianes\AdminUtilities;

/**
 * Add condicional notice in admin (example)
 *
 * @since 1.0.0
 *
 * @return void
 */
function add_admin_notice(){

    $admin_page_with_notice = 'index.php';
    $user_role_for_notice = 'administrator';

    global $pagenow;

    if ( !($pagenow == $admin_page_with_notice) ) {
    	return;
	}
    
    $current_user = wp_get_current_user();

    if ( !in_array( $user_role_for_notice , (array) $current_user->roles ) ) {
    	return;
    }

    printf('<div class="notice notice-info is-dismissible">
          <p>Click on <a href="edit.php">Posts</a> to start writing.</p>
          <h1>HELLO WORLD!! This page is %s and you are %s</h1>
         </div>', 
	   $admin_page_with_notice, $user_role_for_notice);
}

add_action('admin_notices', __NAMESPACE__ . '\add_admin_notice', 11);


/**
 * Delete all admin notices except for one user_ID
 *
 * @since 1.0.0
 *
 * @return void
 */
 function delete_all_admin_notices() {
    $admin_user_ID_with_notices = '1';
    $user_role_for_notices = 'administrator';
 	
    $current_user = wp_get_current_user();
    $current_user_data = $current_user->data;

    if ( in_array( $user_role_for_notices, (array) $current_user->roles ) 
    	&& $current_user_data->ID == $admin_user_ID_with_notices ) {
    		return;
    }
    
 	remove_all_filters( 'admin_notices');
	
}

add_action('admin_init',  __NAMESPACE__ . '\delete_all_admin_notices', 999);

Genial David! Ya lo he cambiado y me convence mucho más así. ¡gracias por tu ayuda!

He editado el código de arriba con las modificaciones. :) Gracias!