Site works cross-browser
To reach the most users, sites should work on every major browser.
Test your site in Chrome, Edge, Firefox, and Safari, and fix any issues that appear in each browser.
If your page is a Progressive Web App, consider using Workbox, a high-level service worker toolkit. Workbox is developed against a cross-browser test suite, and when possible, automatically falls back to alternative implementations of features that are missing from certain browsers:
workbox-broadcast-cache-updatemodule uses the Broadcast Channel API if possible and falls back to a
workbox-background-syncmodule uses the Background Sync API if possible and falls back to retrying queued events each time the service worker starts up.
Learn more in Workbox: your high-level service worker toolkit.
In the Lighthouse report UI the full PWA badge is given when you pass all of the audits in all of the PWA subcategories (Fast and reliable, Installable, and PWA optimized).