handle requests in MVC pattern with php

Question

I was reading this question about how to manage the form submission in php mvc applications.

I'm trying to create a routing system to learn more about MVC and php and I want to use RedBeanPHP as the main ORM. I'm not a master with the mvc pattern in php, so I've the following code that is supposed to instantiate the relative controller when an url is requested. Can someone show me a correct implementation without a framework, of the concept? Another doubt is about RedBean. Will be loaded on every controller if i setup it on the front controller?

<?php

declare( strict_types = 1 );

require_once __DIR__.'/vendor/autoload.php';

use \RedBeanPHP\R;

$dbh = R::setup();

class Router {

  public static function init()
  {
    $uri = trim(parse_url( $_SERVER['REQUEST_URI'], PHP_URL_PATH ), '/');
      if( $uri != '' ){
        list( $controller, $method, $args ) = explode( '/', $uri, 3 );
          $controller = ucfirst( $controller ).'Controller';
            if( class_exists( $controller ) ){
              if( !isset($args) ){
                call_user_func([new $controller, $method]);
              }
              call_user_func_array( new $controller, $method, [$args] );
            }
      }
      else{
        IndexController::index();
      }
  }

}


class IndexController {

  public static function index()
  {
    //include TEMPLATE_PATH.'/index.php';
    echo 'Hello index';
  }

}

class UserController {

  public function demo()
  { 
    //include TEMPLATE_PATH.'/test.php';
    echo 'Hello demo';
  }

}

?>

I'm not sure if this is the right way to apply the mvc pattern, this also because if there is a form inside the loaded view template, I'm not sure how to manage it, what is the correct <form action="" > to set. This also because I will implement redbean with the FUSE models to validate the data.