$api = ShopifyApp::api();
// Define the query.
$query =
'{
   shop
   {
      products(first: 1)
      {
         totalCount
      }
   }
}';
$response = $api->graph(GraphqlEnum::ADMIN_API, new GraphqlValue($query));
// Total count of products.
$totalCount = $response['data']['shop']['products']['totalCount'];