Export Chrome Search Engine to a Json File, and Import into Brave

DownloadSearchEngineJson.js

/*
 * Source: https://superuser.com/a/1626575
 * 2021/07/22 Tested successfully on Chrome Version 91.0.4472.164 (Official Build) (x86_64) on Mac
 * Usage: 
 *   1. Open `chrome://settings/searchEngines` on Chrome
 *   2. Open Developer Tools (Cmd+Opt+i)
 *   3. Choose `Console` tab
 *   4. Paste code below and save as a json file
 */
(function exportSEs() {
  /* Auxiliary function to download a file with the exported data */
  function downloadData(filename, data) {
    const file = new File([data], { type: 'text/json' });
    const elem = document.createElement('a');
    elem.href = URL.createObjectURL(file);
    elem.download = filename;
    elem.click();
  }

  let searchEngines = [];
  document.querySelector('settings-ui').shadowRoot
    .querySelector('settings-main').shadowRoot
    .querySelector('settings-basic-page').shadowRoot
    .querySelector('settings-search-page').shadowRoot
    .querySelector('settings-search-engines-page').shadowRoot
    .querySelector('settings-search-engines-list#otherEngines').shadowRoot
    .querySelectorAll('settings-search-engine-entry')
    .forEach($el => searchEngines.push(
      {
        name: $el.shadowRoot.querySelector('#name-column').textContent,
        keyword: $el.shadowRoot.querySelector('#keyword-column').textContent,
        url: $el.shadowRoot.querySelector('#url-column').textContent
      })
    )

  downloadData('search_engines.json', JSON.stringify(searchEngines));
}());

ImportSearchEngineToBrave.js

/*
 * Source: https://superuser.com/a/1626575
 * 2021/07/22 Tested successfully on Brave Version 1.26.77 Chromium: 91.0.4472.164 (Official Build) (x86_64) on Mac
 * But not all imported, most of engines imported.
 */
(async function importSEs() {
  /* Auxiliary function to open a file selection dialog */
  function selectFileToRead() {
    return new Promise((resolve) => {
      const input = document.createElement('input');
      input.setAttribute('type', 'file');
      input.addEventListener('change', (e) => {
        resolve(e.target.files[0]);
      }, false);
      input.click();
    });
  }

  /* Auxiliary function to read data from a file */
  function readFile(file) {
    return new Promise((resolve) => {
      const reader = new FileReader();
      reader.addEventListener('load', (e) => {
        resolve(e.target.result);
      });
      reader.readAsText(file);
    });
  }

  const file = await selectFileToRead();
  const content = await readFile(file);
  const searchEngines = JSON.parse(content);
  searchEngines.forEach(({ name, keyword, url }) => {
    /* Actual search engine import magic */
    chrome.send('searchEngineEditStarted', [-1]);
    chrome.send('searchEngineEditCompleted', [name, keyword, url]);
  });
}());