function doGet() {
  const text = UrlFetchApp.fetch(
    'https://raw.githubusercontent.com/ajgpw/youtube/refs/heads/main/index.html.txt'
  ).getContentText();
  return HtmlService.createHtmlOutput(text)
                    .setTitle('しあtube')
                    .setXFrameOptionsMode(HtmlService.XFrameOptionsMode.ALLOWALL);
}


<script defer data-domain="html.cafe" src="https://milkymouse.com/js/script.js"></script>