You can archive this using
Create form like 'Request Order datail for guest customer' with input box email and call function as per below.
public function __construct(
\Magento\Sales\Model\ResourceModel\Order\CollectionFactory $orderCollectionFactory,
) {
$this->orderCollectionFactory = $orderCollectionFactory;
}
public function getGuestOrderCollection()
{
$post = $this->getRequest()->getPost();
$Customeremail = $post['email'];
$orderCollecion = $this->orderCollectionFactory
->create()
->addFieldToSelect('*');
$orderCollecion->addAttributeToFilter('customer_email',$Customeremail)
$orderCollecion->addAttributeToFilter('customer_is_guest', ['eq'=>1]);
$orderData = $orderCollecion->getData();
//Get Last Ordered details from $orderData and send order details using mail to guest email
return $orderCollecion;
}