function prefix_get_endpoint_phrase() {
    // rest_ensure_response() wraps the data we want to return into a WP_REST_Response, and ensures it will be properly returned.
    $url1 = 'https://forblitz.ru/wp-json/wp/v2/posts?sticky=true'; // path to your JSON file
	$url2 = 'https://forblitz.ru/wp-json/wp/v2/posts?per_page=30&categories_exclude=1'; // path to your JSON file
	$json1 = file_get_contents($url1);
	$json2 = file_get_contents($url2);

	$my_array1 = json_decode($json1, true);
	$my_array2 = json_decode($json2, true);
	$res = array_merge($my_array1, $my_array2);
    return $res;
}
 
/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_example_routes() {
    // register_rest_route() handles more arguments but we are going to stick to the basics for now.
    register_rest_route( 'wp/v1', '/posts', array(
        // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
        'methods'  => WP_REST_Server::READABLE,
        // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
        'callback' => 'prefix_get_endpoint_phrase',
    ) );
}
 
add_action( 'rest_api_init', 'prefix_register_example_routes' );