Best way to create a page outside of the pages list

Such an interesting question, I will be keen to see the other responses.

I am sure their is a more elegant solution but I would just hook into the wp admin css and hide those pages from the users view like this.

    // Hook into the admin head
    add_action('admin_head', 'hidepages_css');

    // Add our custom CSS to the admin pages
    function hidepages_css() { ?>

    <style>

/*Each page entry is within a table (table has a class of .pages) and has a unique ID, use your browsers inspect element to find the ID of the pages you want hidden from users view */

    .pages #post-5, .pages #post-9,  {
        display: none !important;
    }

    </style>

    <?php } ?>

You can also set it so that only you can see the pages as an admin but your users with lower roles cant.

// Check if the user is an admin
    if ( ! current_user_can( 'manage_options' ) ) {
        // Hook into the admin head
    add_action('admin_head', 'hidepages_css');

    // Add our custom CSS to the admin pages
    function hidepages_css() { ?>

    <style>

    .pages #post-5, .pages #post-9,  {
        display: none !important;
    }

    </style>

    <?php } ?>
    }