@return description in magento-coding-standard

I am currently working on bringing my extensions to the current coding standard.

So, when writing a function, normally I would describe it the following way:

protected function exampleFunction(string $name): string|null
{
   return $name;
}

But there are some cases, where I dont know, how to "describe" the return value.

For example:

protected function getParentProduct(int $id): ??????
    {
        $parentByChild = $this->catalogProductTypeConfigurable->getParentIdsByChild($id);
        if (isset($parentByChild[0])) {
            //set id as parent product id...
            $parentid = $parentByChild[0];
            return $this->ProductFactory->create()->load($parentid);
        }
    }

So, the function returns a loaded product (built with ProductFactory. But as the Product-class is not explicity at the begin of the class (Magento\Catalog\Model\Product), I dont know, what I should use for the description or if its ok, to just write:

protected function getParentProduct(int $id): Product|null

I know, this is nothing, that would break the code, but I want to use more good habits, when coding my extensions.