The right way to do this

I want to make an app where I want to store some info like ID, start_date, end_date, name, and item in firebase so I can via Zapier make an event in google calender for future notification with Onesignal, when the event triggers.
But I need to see the same list witk the same info in a list in the app the next time I open the app.
The reason to also use Firebase and google calender is that I want the notification also if the App is closed.
The easyest way is to put the event up in the phones calender but dont think that is possible or is it???