WooCommerce Display Specific "Out of Stock" Products on Shop Pages

/**
* @Title: WooCommerce Display Specific "Out of Stock" Products on Shop Pages
* @Author: Mina Pansuriya
* @Website: http://minapansuriya.com
* Note: For complete tutorial visit: http://minapansuriya.com/woocommerce-display-selected-out-of-stock-products-on-shopcategory-pages/
*/
add_filter( 'woocommerce_product_is_visible', 'pbs_woo_disp_selected_out_of_stock_products', 2, 99 );

function pbs_woo_disp_selected_out_of_stock_products( $visible, $productId ) {
    
    // Replace "6838" with your product post ID. If you want to hide multiple no. of out of stock products, 
    // add further product IDs in this if statement comparision.
    if($productId == 6838)
    {
       // All the product here will be displayed.
    }
    else
    {
        $product = new WC_Product($productId);
        if(!$product->is_in_stock())
        {
            $visible = false;
        }
    }
    return $visible;
}