Using rewrite rule to access a view of a plugin from home page

This will create / handle your endpoint and attempt to load your php if the file is readable. Note: you won’t want to refresh the rewrite rules here but it’ll make sure you can test quickly.

if (!class_exists('WPTestPluginEndpoint')):

    class WPTestPluginEndpoint
    {
        const ENDPOINT_QUERY_NAME = '__my_test_plugin';

        // WordPress hooks

        public function init()
        {
            add_filter('query_vars', array($this, 'add_query_vars'), 0);
            add_action('parse_request', array($this, 'sniff_requests'), 0);
            add_action('init', array($this, 'add_endpoint'), 0);
        }

        // Add public query vars
        public function add_query_vars($vars)
        {
            $vars[] = static::ENDPOINT_QUERY_NAME;

            return $vars;
        }

        // Add API Endpoint

        public function add_endpoint()
        {
            $query_name = self::ENDPOINT_QUERY_NAME;
            add_rewrite_rule('^wp-test-plugin/?', "index.php?{$query_name}=1", 'top');

//////////////////////////////////////
//////////////////////////////////////
// don't do this all the time!!!
//////////////////////////////////////
flush_rewrite_rules(false);
//////////////////////////////////////
//////////////////////////////////////
        }

        // Sniff Requests

        public function sniff_requests()
        {
            global $wp;
            if (isset($wp->query_vars[ self::ENDPOINT_QUERY_NAME ])) {
                $this->handle_request(); // handle it
                exit;
            }
        }

        // Handle Requests

        protected function handle_request()
        {
            $public_display = WP_PLUGIN_DIR . '/wp-test-plugin/public/partials/wp-test-plugin-public-display.php';

            if( is_readable( $public_display )) {

                require $public_display;

            }
            else {

                wp_die("Can't find Render Page ". $public_display );

            }

            die(); // nothing to be done
        }
    }

    $wptept = new WPTestPluginEndpoint();
    $wptept->init();

endif; // WPTestPluginEndpoint