The guy who founded owncloud (Frank), sold it to american venture capitalists. When Frank didn’t like how the VCs were planning to enshittify Owncloud, he forked the project and moved it back to Germany from Boston. The American VCs saw this, realized they couldn’t exploit the software anymore, so they sold Owncloud to a group of German businessmen. Ironically for Frank there are now two german owned non-VC backed cloud software based on the same code. But yeah they’re taking different strategic paths for growth.
You should look at JTX Board. It’s associated with DAVx5 and they do the vjournal and vtodo standards. They have a list of services that support it. https://jtx.techbee.at/sync-with-davx5