I also use Nextcloud as the backend and iOS Calendar app as frontend on mobile and Gnome Calendar as frontend on PC.
It mostly works great, except for 3rd party Office365 calendars imported into Nextcloud. It has issues with some events on some clients displaying correct time when event invitees are from different time zone.
It mostly works great, except for 3rd party Office365 calendars imported into Nextcloud. It has issues with some events on some clients displaying correct time when event invitees are from different time zone.