Don't know what the content is of this file seems the https://github.com/jboss-mobile/unified-push-helloworld/pull/31 demo doesn't have this google-services.json

yes, that's correct. It's up to the developer to actually put the file into that "/app" folder.

Would this work on Cordova too ?

So the content would be app specific? Could you give an example? We can put some dynamic stuff into the plugin, but it's kinda limited. I hope we can do without having cordova devs worry about the platform folder.