Changing from SQLite to Mariadb, also how to transfer SQLite DB to new install


I’ve been a bit silly.
New OMV 4 with Nextcloud 16 and Mariadb containers. I Started up Nextcloud, selected mysql and finished the nextcloud config, even had a look at federation and installed some apps. Shut the OMV server down to work with it later.

When I started it again and accessed Nextcloud I was faced with the set password and configure database initialising screen again. Dozy me typed in the previously set username and password, then clicked ‘finish’ and I now have a permanent SQLite database not the Mysql originally intended.

Can I reset the installation easily and use Mysql as originally intended? I’m hoping not to have to delete and reinstall. The Databases have no data, so there is nothing to lose as far as I know at the moment :o)

I have Nextcloud 11 on an asustor NAS that I want to decommission. That is running SQLite and holds photographs and a calendar. What is the best way to transfer that data to my new Nextcloud 16 server? Should I transfer data SQLite to SQLite while both installations have similar databases or somehow migrate the data after reinstating Mysql?

Thank you for your help.