You can find updated browser support page here.

Android Chrome browser has best support for PWA.

Android Chrome & Edge browser Automatically shows PWA Install Prompt.

While other browsers like Firefox, iOS Safari has add to homescreen feature but doesn't show install prompt automatically.

Firebase Web Push Notification supports in Android Chrome, Android Firefox & Desktop Chrome on Windows. iOS Safari doesn't support yet.

PWA Splash Screen supports in Android Chrome & iPhone Safari Browser (iOS 11.4+).

Desktop PWA supports in Windows Chrome & Edge browser.

Web Share API supports in Android Chrome Browser & iPhone Safari Browser (iOS 12.2+).