/**
  * Function to Add SKU to Category Pages
  * Date: July 15, 2020
  * King Rosales
  */

add_action( 'woocommerce_after_shop_loop_item_title', 'woocommerce_after_shop_loop_item_sku_in_cart', 20, 1);
function woocommerce_after_shop_loop_item_sku_in_cart( $template ) {
global $product;
$sku = $product->get_sku();
echo $sku;
}