Router

Files

etc/frontend/di.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
	<type name="Magento\Framework\App\RouterList">
		<arguments>
			<argument name="routerList" xsi:type="array">
				<item name="" xsi:type="array">
					<item name="class" xsi:type="string">Mage2Gen\Module\Controller\Router</item>
					<item name="disable" xsi:type="boolean">false</item>
					<item name="sortOrder" xsi:type="string">999</item>
				</item>
			</argument>
		</arguments>
	</type>
</config>

Controller/Router.php

<?php
declare(strict_types=1);

namespace Mage2Gen\Module\Controller;

use Magento\Framework\App\ActionFactory;
use Magento\Framework\App\Action\Forward;
use Magento\Framework\App\RequestInterface;
use Magento\Framework\App\RouterInterface;

class Router implements RouterInterface
{

    protected $transportBuilder;
    protected $actionFactory;

    /**
     * Router constructor
     *
     * @param ActionFactory $actionFactory
     */
    public function __construct(ActionFactory $actionFactory)
    {
        $this->actionFactory = $actionFactory;
    }

    /**
     * {@inheritdoc}
     */
    public function match(RequestInterface $request)
    {
        $result = null;
        
        if ($request->getModuleName() != 'example' && $this->validateRoute($request)) {
            $request->setModuleName('example')
                ->setControllerName('index')
                ->setActionName('index')
                ->setParam('param', 3);
            $result = $this->actionFactory->create(Forward::class);
        }
        return $result;
    }

    /**
     * @param RequestInterface $request
     * @return bool
     */
    public function validateRoute(RequestInterface $request)
    {
        $identifier = trim($request->getPathInfo(), '/');
        return strpos($identifier, '') !== false;
    }
}