Nullstack can be used as to build a Chrome Extension.

These are all the changes required to make the app compatible as an extension:

• public/manifest.json creates the Chrome Extension manifest file
• server.js disables the default service worker, as the extension doesn't need it
• src/Application.jsx is the entry component that will render the Popup code
• package.json sets mode to SPA (default mode) and enables writing files to disk

You can find a full example at Mortaro/nullstack-chrome-extension.