..., but if it is not possible, do you know of a simple reminder app that does not ask for full Internet access?
The topic is also discussed in the Google forum for the calender application and indeed there seem to be only workarounds.
There is also an app mentioned, which does provide the notifications for the birthdays and does not need Internet access: https://play.google.com/store/apps/details?id=de.noyer.consulting.contactevents.pro
That is a paid app for a small amount, but there is also a free version with Internet access for advertisements: https://play.google.com/store/apps/details?id=de.noyer.consulting.contactevents.free
If you just want to try the free version if it works for you without even risking to lose your data, you cancould perform the following steps:
- Download the free app in the Play Store
- Turn your device into flight mode
- Start the app
- In Android 6 or higher: Grant access to adress book at first start
- Check the app, widget etc. (Notifications are only raised at midnight)
- Uninstall the app
- Turn off flight mode
- Decide if it worth to get the Pro version