After creating a Progressive Web App, the next thing is to Test it. This guide helps you to debug your progressive web apps with Chrome Dev Tools.
Once the Progressive Web App is launched, right click and on the pop up, select inspect. Dev Tools are launched. Click the two arrows next to Memory in the Dev Tools Panel and select Application or to automatical launch the Application panel in Windows, press Ctrl + Shift + I
Once in the Application Tab, Select Service Workers and click console to check if the service worker is registered.
If registered, then you're good to go! Now select Manifest. Check if all icons are loaded. Look at your Progressive Web App Name, Short Name e.tc. If that's the case, you've a Progressive Web App : )
Now while still in the Manifest Panel, click Add to homescreen. It should prompt you to Add add to homescreen. This will be as a Desktop Progressive Web App. Or you could just click the three vertical dots at the top-right corner of the Chrome Browser. Select Install "Your App Name".
Still in the Application Panel, you can check the cache and a lot more of things to spark off a great a Progressive Web App. You could also debug with your mobile device using the guide in this progressive web app checklist doc.
To get deeper into it, checkout a detailed progressive web app checklist available on this dev site doc by Google Developers.
Finally, use Google's progressive web app audit tool. It has audits for performance, accessibility, progressive web apps and much more here.