I have the same issue as others regarding loading the OneSignal cordova plugin. The plugin fails to initialize when it's called per the OneSignal instructions. The app just hangs there.
Since I wasn't successful here with OneSignal, I pursued the Firebase option and found there's no way to load the required .json file necessary to load the Firebase plugin. So dead end there too.
I'm now back on trying to get the OneSignal plugin to load properly. I've loading the project in Android Studio in order to do debugging, but the Appery Export won't load properly in the current version of Android Studio.
I was able to load my Appery project in xCode, but there's no output from Xcode showing the issue as I run the Xcode simulator. The app just hangs as it tries to load the OneSignal plugin.
I've contacted OneSignal and they aren't familiar with Appery.io, so they aren't able to help.
Any help would be greatly appreciated.
Thanks,
Steve