TYPO3 - Render extension plugin output via Typoscript

I'm using TYPO3 13.1.1 and I delevoped a custom extension in order to display on the front-end side some stuff generated by one of my extension Controller.

-> My extension was installed via Composer, and is displayed in the Extension back-end tab. -> For the moment, I just need to output a "Hello World!" via a plugin

What I see on the front-end : Error "Oops, an error occurred"

My ProductSpaceController.php:

<?php

namespace Company\Controller;
use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;

class ProductSpaceController extends ActionController
{
    public function testAction()
    {
        return 'Hello World';
    }
}

My ext_localconf.php:

<?php

declare(strict_types=1);

use MyCompany\Controller\ProductSpaceController;
use TYPO3\CMS\Extbase\Utility\ExtensionUtility;

defined('TYPO3') or die('Access denied.');

ExtensionUtility::configurePlugin
(
    'company',
    'displaymatrice',
    [
        ProductSpaceController::class => 'test',
    ],
    [
        ProductSpaceController::class => 'test',
    ]
);

My Configuration/Services.yaml:

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

  Company\:
    resource: '../Classes/*'

My typoscript:

lib.testoutput = USER_INT // I also tried COA, USER
lib.testoutput < tt_content.list.20.company_displaymatrice

When I try to display in fluid, I get the error:

<f:cObject typoscriptObjectPath="lib.testoutput" />

PS: I have other "lib.xxx" that already work (for my top menu, my footer menu, my breadcrumb, my lang switcher etc...)

Solution

As Julian Hofmann mentioned above tt_content.list.20.company_displaymatrice already contains the needed EXTBASEPLUGIN object.

So you don't need this line in your TypoScript:
lib.testoutput = USER_INT // I also tried COA, USER

Since TYPO3 12 it's mandatory, that controller actions returns an instance of ResponseInterface. See here:
https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/ExtensionArchitecture/Extbase/Reference/Controller/ActionController.html#actions

So your action needs to look like this:

public function testAction()
{
    return $this->htmlResponse('<p>Hello World</p>');
}