As of 2021, PWA features are supported to varying degrees by Google Chrome, Apple Safari, Firefox for Android, and Microsoft Edge but not by Firefox for desktop.

Does Firefox support PWA?

You may not need to switch to Chromium browsers for this, you can still install, manage and use PWAs in the Firefox browser, thanks to developers for making this possible with the FirefoxPWA project (unofficial). Firefox on Android supports PWA, it's the desktop version that doesn't.

Is Chrome a PWA?

Chrome itself lists installed PWAs as well and provides users with management options. Google made the decision to integrate them with apps in the browser which means that you can display all installed PWA by loading chrome://apps/ in the browser's address bar.