I\'m currently re-working an app of mine which updates it\'s internal SQLite database by fetching raw data from an website, not an official API.
As this is quite err
FCM would be a great choice for you considering that using only push data without notification as this forces the sent to data to be received in the onReceive method in your mobile application. If your device is offline it will resend the data again while it comes online again.
Whenever any change happens in your backend send push data to your devices using their presaved tokens.