your_extension.module

<?php

/**
 * @file
 * Code for your_extension module.
 *
 * This module adds a content, set in the configuration form, to the bottom of
 * the page and shows it if JavaScript is disabled.
 */

declare(strict_types=1);

/**
 * Implements hook_page_bottom().
 */
function your_extension_page_bottom(array &$page_bottom) {
  /** @var \Drupal\your_extension\YourExtensionService $your_extension_service */
  $your_extension_service = \Drupal::getContainer()->get('your_extension.service');

  $text = $your_extension_service->getText();

  if (!empty($text)) {
    $page_bottom['your_extension'] = [
      '#type' => 'html_tag',
      '#tag' => 'noscript',
      '#value' => $text,
    ];
  }
}