I want to get the product information like **product id, sku** at admin(backend), When action is being performed on any order. How can I achieve this. 

**This is code:**

    <?php
        
    namespace Custom\Confirm\Controller\Adminhtml\Order;
    
    use Magento\Framework\Controller\ResultFactory;
    use Magento\Backend\App\Action\Context;
    use Magento\Ui\Component\MassAction\Filter;
    use Custom\Confirm\Model\ResourceModel\Saleslist\CollectionFactory;
        
    /**
     * Class Payseller.
     */
    class MassConfirm extends \Magento\Backend\App\Action
    {
    	 /**
         * @var \Magento\Sales\Api\OrderRepositoryInterface
         */
        protected $_orderRepository;
     
        /**
         * @var \Magento\Sales\Model\Service\InvoiceService
         */
        protected $_invoiceService;
     
        /**
         * @var \Magento\Framework\DB\Transaction
         */
        protected $_transaction;
    	
    	protected $_order;
     
        public function __construct(
            \Magento\Framework\App\Action\Context $context,
            \Magento\Sales\Api\OrderRepositoryInterface $orderRepository,
            \Magento\Sales\Model\Service\InvoiceService $invoiceService,
    		\Magento\Sales\Model\Order $orderInfo,
            \Magento\Framework\DB\Transaction $transaction
        ) {
            $this->_orderRepository = $orderRepository;
    		$this->_order = $orderInfo;
            $this->_invoiceService = $invoiceService;
            $this->_transaction = $transaction;
            parent::__construct($context);
        }
       
        /**
         * Execute action.
         *
         * @return \Magento\Backend\Model\View\Result\Redirect
         *
         * @throws \Magento\Framework\Exception\LocalizedException|\Exception
         */
        public function execute()
        {
    			/** @var \Magento\Backend\Model\View\Result\Redirect $resultRedirect */
            $resultRedirect = $this->resultRedirectFactory->create();
    		
    		$wholedata = $this->getRequest()->getPost();
    		
    		foreach ($wholedata['selected'] as $orderId){
    		
    		
    		 $order = $this->_orderRepository->get($orderId);
    			
    			
    				$order2=$this->_order->load($orderId);
    				$items = $order2->getAllItems();
    				echo $orderId;
    				//var_dump($items);
    				foreach($items as $i){
    				 //var_dump($i);
                     // code to retrieve product id 
    				}
                
    				
    				  $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
    				$order_ = $objectManager->create('\Magento\Sales\Model\Order')
    										   ->load($orderId); 
    				 
    				$order_->setState("processing")->setStatus("processing");
    				 
    				$order_->save();  
    			
    		}	
    		$this->messageManager->addSuccess(__('The order has been confirm. '));
    		return $resultRedirect->setPath('sales/order/index');
        }
    
    }

Thanks in advance.