OK to init WP by manually incl. wp-config, functions, classes & plugins.php?

Hey!

I am making a plugin with a file that is to be accessed directly from a device.
It initializes wordpress manually (to get access to the functions) by doing this:

// Get necessary stuff to access wordpress' functions
define('ABSPATH', dirname(dirname(dirname(dirname(__FILE__)))) . '/');
require_once(ABSPATH .'/wp-config.php');
require_once(ABSPATH .'/wp-includes/classes.php');
require_once(ABSPATH .'/wp-includes/functions.php');
require_once(ABSPATH .'/wp-includes/plugin.php');
$wp->init();

Is this okay, or could it harm wordpress in any way?

Thank you.