This is a tester for wp rest api authentication. You can call against unsecured and it'll always work, but change to secured and it'll only work for authed admins.

myhacks.php

<?php

add_action( 'rest_api_init', 'myhacks_init' );
function myhacks_init() {

	register_rest_route( 'myhacks', '/unsecured', array(
		'methods' => 'GET',
		'callback' => 'myhacks_response',
	) );

	register_rest_route( 'myhacks', '/secured', array(
		'methods' => 'GET',
		'callback' => 'myhacks_response',
		'permission_callback' => 'myhacks_permission_callback',
	) );

}

function myhacks_response() {
	return array( 'doowop' => 'Data wants to be free, yo?' );
}

function myhacks_permission_callback() {
	return current_user_can( 'manage_options' );
}

Thank you! Worked well 👍