Ah, wish I had known that a few days ago. Is there a really easy way to backup contact/calendar/message data on the regular OS and restore them on the FP OS, via SD card? Because moving from FP1 to FP2 was such a pain, I don’t want to repeat this experience.
Do you still have the FP1 with the data on it. That would be easiest because then you could use Titanium Backup.
If not I believe there is also a quite easy way to export the data from the Google cloud, but someone else would have to explain that to you.
I recently upgraded my ownCloud instance to NextCloud and did a local backup of my data, so I think I can help you with the transition to FP Open. First of all, install F-Droid to download below cited apps:
Contacts: Open your Contacts app → Open the three-points menu → Import/export. I’ve discovered that this only seems to work with an SD card (urg, I should report that bug). If it doesn’t, just use Export Contacts.
SMS messages: I usually use SMS Backup & Restore, whichs is a proprietary app. To me it doesn’t matter very much because I cut its access to internet with NetGuard for privacy reasons. Slight Backup seems to be a libre alternative, but I can’t guarantee it works great.