Prayer Times Notifications - Local or OneSignal?

Hi,

I have an app for prayer time notifications which will notify the user five times a day (not fixed times).

I will download the prayer times to the device and save it using SettingsPlugin so it will have it locally,

But what's the best practice to send the notification to the user?

Shall I Send local notification from my iOS and Android? or use OneSignal to send the notifications?

and if I send locally then how will I be able to track or check the analysis?

Kindly advise..

Thanks,
Jassim