How to use services defined in PHP-DI in the Symfony's services.yaml?

Question

I'm writing an application, that has a structure of a Symfony application and some Symfony functionality, but should be decoupled from the framework as possible. So instead of the framework's DI, I'm using PHP-DI.

Now I need Symfony's EventDispatcher (a bitter pill for my framework-decoupled architecture, but anyway...). My Problem is, that I'm not getting referencing from the services.yaml to the PHP-DI container working -- and my listeners aren't gettin attached to the EventDispatcher.

How to use PHP-DI container's services in the services.yaml (especially for the EventDispatcher, if it has any specifics)?

---

Here is some code:

services.yaml (completely)

parameters:

services:
    _defaults:
        autowire: true
        autoconfigure: true
        public: false

    # events
    # App\Process\SystemEventHandler: <-- No errors, but also no effect.
    @system.event_handler:
        tags:
            - { name: system.event_handler, event: general.user_message_received, method: handle }
            - { name: system.event_handler, event: xxx.foo, method: handle }
            - { name: system.event_handler, event: yyy.foo, method: handle }
            - { name: system.event_handler, event: zzz.foo, method: handle }

App\Kernel (completely)

namespace App;

use DI\Bridge\Symfony\Kernel as PhpDIBridgeSymfonyKernel;
use DI\Container;
use DI\ContainerBuilder as PhpDiContainerBuilder;
use Exception;
use Psr\Container\ContainerInterface;
use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
use Symfony\Component\Config\Exception\FileLoaderLoadException;
use Symfony\Component\Config\Loader\LoaderInterface;
use Symfony\Component\Config\Resource\FileResource;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\Routing\RouteCollectionBuilder;

class Kernel extends PhpDIBridgeSymfonyKernel
{
    use MicroKernelTrait;

    const CONFIG_EXTS = '.{php,xml,yaml,yml}';

    public function getCacheDir()
    {
        return $this->getProjectDir().'/var/cache/'.$this->environment;
    }

    public function getLogDir()
    {
        return $this->getProjectDir().'/var/log';
    }

    public function registerBundles()
    {
        $contents = require $this->getProjectDir() . '/config/bundles.php';
        foreach ($contents as $class => $envs) {
            if (isset($envs['all']) || isset($envs[$this->environment])) {
                yield new $class();
            }
        }
    }

    /**
     * @param ContainerBuilder $container
     * @param LoaderInterface $loader
     * @throws Exception
     */
    protected function configureContainer(ContainerBuilder $container, LoaderInterface $loader)
    {
        $container->addResource(new FileResource($this->getProjectDir().'/config/bundles.php'));
        // Feel free to remove the "container.autowiring.strict_mode" parameter
        // if you are using symfony/dependency-injection 4.0+ as it's the default behavior
        $container->setParameter('container.autowiring.strict_mode', true);
        $container->setParameter('container.dumper.inline_class_loader', true);
        $confDir = $this->getProjectDir().'/config';

        $loader->load($confDir.'/{packages}/*'.self::CONFIG_EXTS, 'glob');
        $loader->load($confDir.'/{packages}/'.$this->environment.'/**/*'.self::CONFIG_EXTS, 'glob');
        $loader->load($confDir.'/{services}'.self::CONFIG_EXTS, 'glob');
        $loader->load($confDir.'/{services}_'.$this->environment.self::CONFIG_EXTS, 'glob');
    }

    /**
     * @param RouteCollectionBuilder $routes
     * @throws FileLoaderLoadException
     */
    protected function configureRoutes(RouteCollectionBuilder $routes)
    {
        $confDir = $this->getProjectDir().'/config';

        $routes->import($confDir.'/{routes}/*'.self::CONFIG_EXTS, '/', 'glob');
        $routes->import($confDir.'/{routes}/'.$this->environment.'/**/*'.self::CONFIG_EXTS, '/', 'glob');
        $routes->import($confDir.'/{routes}'.self::CONFIG_EXTS, '/', 'glob');
    }

    /**
     * @param PhpDiContainerBuilder $builder
     * @return Container|ContainerInterface
     * @throws Exception
     */
    protected function buildPHPDIContainer(PhpDiContainerBuilder $builder)
    {
        // Configure your container here
        // http://php-di.org/doc/container-configuration.html
        $builder->addDefinitions($this->getProjectDir() . '/config/dependencies/common.php');

        return $builder->build();
    }

}

/config/dependencies/common.php (file with the dependencies, relevant extract)

...
return [
    FooServiceInterface::class => DI\autowire(FooBService::class),
    BarServiceInterface::class => DI\autowire(BarService::class),
    ...
    EntityManagerInterface::class => function () {
        ...
    },
    'process_handler.xxx' => DI\autowire(XxxHandler::class),
    'process_handler.yyy' => DI\autowire(YyyHandler::class),
    'process_handler.zzz' => DI\autowire(ZzzHandler::class),
    EventHandlerInterface::class => DI\factory(function(ContainerInterface $container) {
        return new SystemEventHandler(
            $container->get('process_handler.xxx'),
            $container->get('process_handler.yyy'),
            $container->get('process_handler.zzz')
        );
    }),
    'system.event_handler' => DI\get(EventHandlerInterface::class),
    EventDispatcherInterface::class => DI\get('event_dispatcher'),
];