I moved all my data to Nextcloud and now I’m figuring out which Android apps I should use to access different features.
Some Nextcloud features like files, deck, and notes have official Android apps. However, there are no official apps for calendar, contacts, and tasks. I’m aware of DAVx5 for syncing, but I still need a separate client.
For tasks, I’ve heard that Tasks.org is popular.
As for calendar and contacts, some default to Google apps, but I’m concerned about privacy since they may share information with Google.
For Android, most calendar apps should suffice, assuming you install DAVx5 which is the one that does the actual syncing in most cases, behind the scenes as it were. Usually the calendar apps that comes pre-installed on your phone should work without issues. This would be the easiest approach.
If you want Calendar app recommendations, I would suggest Etar or Fossify Calendar, both free from F-Droid. Both open source and both respect your privacy.
As far as contacts, same thing applies as above, DAVx5 will also sync your contact with your NC instance. How? Because DAVx5 syncs contact and calendar databases on Android, which your apps draw upon in order to display the info. There is Fossify Contacts, for example, but then again, the pre-installed app that comes with your phone should suffice.