react PWA manifest must have path to html file?

Currently, I do not have html file instead I am using html.js. However, start_url in the manifest.json seems to take only path to html.

I have been went through may postings from medium which all of them using html. Is this current limit for the pwa ? or there is way to use html.js file as start_url ??


  "short_name": "React App",
  "name": "Create React App Sample",
  "icons": [
      "src": "/static/icon-192.png",
      "sizes": "192x192",
      "type": "image/png"
  "start_url": ".",
  "display": "standalone",
  "theme_color": "#000000",
  "background_color": "#ffffff"