Background

Until TYPO3 v9 it was possible to put controllers and fluid templates for the corresponding controller actions into subfolders like this:

Classes/Controller/Product/CarController.php

namespace Vendor\MyExtension\Controller\Product;

class Car extends AbstractProduct {
   public function listAction(){
      // ...
   }
}

ext_localconf.php

ExtensionUtility::configurePlugin(
    'MyExtension',
    'CarsPlugin',
    ['Product\Cars' => 'list'],
    []
);      

Because of the controller name "Product\Cars" the relative fluid template path would be resolved to this:

typo3conf/ext/my_extension/Resources/Private/Templates/Product/Cars/List.html

In TYPO3 v10 this does not work anymore. I guess it's because now your supposed to give a fully qualified controller name like this:

ext_localconf.php

ExtensionUtility::configurePlugin(
    'MyExtension',
    'CarsPlugin',
    [\Vendor\MyExtension\Controller\Product\CarController::class => 'list'],
    []
);

Now, TYPO3 only tries to relove this template: /typo3conf/ext/my_extension/Resources/Private/Templates/Car/List.html

Question

Is there a way for TYPO3 v10 to aknowledge the controller is in a subfolder and resolve the template, also checking the right subfolder?

It makes life that much easier when the file structure is the same. I also think that's especially important when representing complex hierarchies with domain models and controllers inheriting from parent classes, allowing the system to scale (think of Product/Airplane, Product/Ship etc.).