You can check a list of called layout XML for specific pages by MagentoFrameworkAppView class.

Call getLayout() method from MagentoFrameworkAppView.php class.

getLayout()->getUpdate()->getHandles() is used for getting all the handles of a page.

You need to add the following code at the end of root index.php file to check XML files.

$objectManager = MagentoFrameworkAppObjectManager::getInstance();
$xmlLayout = $objectManager->get(MagentoFrameworkAppView::class);
var_dump($xmlLayout->getLayout()->getUpdate()->getHandles());

To check for a specific page, You need to call the function as below:

public function __construct(
    MagentoFrameworkAppViewInterface $view
) {
    $this->view = $view;
}

Call Inside a function,
$loadedHandles = $this->view->getLayout()->getUpdate()->getHandles();

Now you can print the result $loadedHandles from above expression.