Firebase messaging without FCM

My Ionic 3 app uses the GooglePlus plugin, the Firebase plugin (cordova-plugin-firebase) for data transactions, and FCM (cordova-plugin-fcm-with-dependecy-updated) for Firebase cloud messaging & push notifications triggered when Firebase data changes.
Can the Firebase plugin be used for cloud messaging? If so, please show me how. I’d like to drop the FCM plugin altogether, as it’s responsible for a lot of build issues, and let Firebase handle the notifications. I’d love to use OneSignal, but it can’t be triggered from Firebase functions when database data changes.
Thanks.

Anyone have an answer for this? I’m really at a standstill until this is resolved! Please help!!

I was able to solve it via this tutorial https://medium.com/@senning/push-notifications-with-ionic-and-cordova-plugin-firebase-ab0c0cad3cc0. Hope this helps someone else out there!