Add a custom Metabox to WooCommerce admin orders with HPOS enabled

use Automattic\WooCommerce\Internal\DataStores\Orders\CustomOrdersTableController;

// Add a custom metabox
add_action( 'add_meta_boxes', 'admin_order_custom_metabox' );
function admin_order_custom_metabox() {
    $screen = class_exists( '\Automattic\WooCommerce\Internal\DataStores\Orders\CustomOrdersTableController' ) && wc_get_container()->get( CustomOrdersTableController::class )->custom_orders_table_usage_is_enabled()
        ? wc_get_page_screen_id( 'shop-order' )
        : 'shop_order';

    add_meta_box(
        'custom',
        'Custom Meta Box',
        'custom_metabox_content',
        $screen,
        'side',
        'high'
    );
}

// Metabox content
function custom_metabox_content( $object ) {
    // Get the WC_Order object
    $order = is_a( $object, 'WP_Post' ) ? wc_get_order( $object->ID ) : $object;

    echo '<p>Number (ID): '.$order->get_order_number().'<p>';
    echo '<a>Test button</a>';
}

// Metabox content
function custom_metabox_content( $object ) {
    // Get the WC_Order object
    $order = is_a( $object, 'WP_Post' ) ? wc_get_order( $object->ID ) : $object;

    echo '<p>
    <label for="number_id">' . __('Number ID') . ':<label><br>
    <input type="text" id="number_id" class="number_id" name="number_id" value="' . $order->get_meta('number_id') . '" />
    <p>';
}

// Save custom field value
add_action( 'woocommerce_process_shop_order_meta', 'save_number_id_value', 20 );
function save_number_id_value( $order_id ) {
    $order = wc_get_order( $order_id ); // Get the WC_Order object
    
    if ( isset($_POST['number_id']) ) {
        $order->update_meta_data('number_id', sanitize_text_field($_POST['number_id']));
        $order->save();
    }
}