How to Debug Ionic WebApp?

With Chrome you can type chrome://inspect into your address bar As soon as you are running your Android app, you can inspect the app when you are running it with the "ionic run android" or "ionic emulate android" command

The version of Android, however, must be higher than 4.3 I think...

According to the documentation there's a few different way's to do this. Also could you try one of these listed below since you have tried ionic serve already?

 ionic run
 ionic emulate

The run or emulate command will deploy the app to the specified platform devices/emulators. You can also run live reload on the specified platform device by adding the --livereload option. The live reload functionality is similar to ionic serve, but instead of developing and debugging an app using a standard browser, the compiled hybrid app itself is watching for any changes to its files and reloading the app when needed. This reduces the requirement to constantly rebuild the app for small changes.

Hope this get's you going! Let me know how it work's out for you.

I found this tool very useful, you can attach your device and get a real time inspector on your Cordova app(for iOS and Android platforms).