WordPress - Hide Login Page with custom hidden $_GET and show website only via Rest API endpoints

gistfile1.txt

<?php

function hide_login_page_and_show_only_rest_api_endpoints() {
  // work only on productions sites
	if (
		!stristr($_SERVER['SERVER_NAME'], 'local')
		&& !is_user_logged_in()
	) {
		if (
			(
				in_array( $GLOBALS['pagenow'], array('wp-login.php', 'wp-register.php') 
				&& isset($_GET['your_custom_get'])
				&& $_GET['your_custom_get'] === 'true'
			) || (
				stristr($_SERVER['REQUEST_URI'], '/wp-json/')
			)
		) {
			// ok
		} else {
			// die
			global $wp_query;
			$wp_query->set_404();
			status_header( 404 );
			nocache_headers();
			die();
		}
	}
}
add_action( 'wp_loaded', 'hide_login_page_and_show_only_rest_api_endpoints' );