Migrate from OwnCloud, keeping calendar and contacts but dropping files


I would like to migrate a small Owncloud 9.1.5 instance to Nextcloud. For testing, I want to install Nextcloud parallel to Owncloud with its own database. I have a pretty good idea of how to do this.

But I would like to keep users, calendar entries and contacts, while not keeping any files. Is there any way to achieve this? I thought about installing Nextcloud with an empty data directory and creating the Nextcloud database from the backup of my Owncloud DB, but then the information about files in the DB would be inconsistent with the empty data directory on disk. Is there any way around this?

The reason I would like to not import any files is that I would like to tidy up some things.

Why not migrate like all others and then delete your files.
Yes, Read your posting.
Please disable versions app, delete your files after migration and your database should be fine.