[Feature] Calendar Sync with Device's Calendar

[JosefSchoenberger]

Is your feature request related to a problem? Please describe.
The old Android Campus app used to synchronize the Campus calendar with my device calendar using the Android Calendar Provider API. This was great, as I have multiple calendars synced on my system (e.g., from NextCloud) and my default device calendar was authoritative over all of them.

Describe the solution you'd like
Restore this functionality again, please.

Describe alternatives you've considered
Campus Online does not offer a CalDAV endpoint that one could use using OpenSync or similar. It only offers an iCal export functionality that software like NextCloud or Thunderbird regularly pull to synchronize the calender. There are iCal synchronization apps for Android, but the original app (iCalSync) is too old to be available and newer alternatives are payware. This option is also read-only.

Additional context
There seem to be flutter packages available to implement something like this; for example, device_calendar could be an option.

[jakobkoerber]

Thank you for your contribution! This sounds like an interesting suggestion that we will have to evaluate further. As other things are more important before the public release on both platforms, I have marked the issue as "low priority" for now.