A JS bookmarklet to get URLs of Google Chat threads

getthread.js

javascript:(function() {
  Array.from(document.getElementsByTagName('c-wiz'))
    .map(tag => ({
      threadId: tag.getAttribute('data-topic-id'),
      firstMessage: tag.children[0].getAttribute('aria-label')
      }))
    .filter(thread => thread.threadId != null && thread.firstMessage != null)
    .forEach(thread => console.log(window.location.href + '/' + thread.threadId
                                   + " : " + thread.firstMessage))
}())

Create a browser bookmark with URL set to the content of the file. Open the bookmark when a tab with Google Chat room is active and it will print the results to the browser console.