Jump versions from 8.0.16 to current

Have here a Windows based owncloud installation (WAMP stack) based on 8.0.16. Works still well and users love it. Now want to move to a new server (Linux this time as no support for Windows any more).

Have moved everything across and edited the config to make fit with Linux. I understand I can only upgrade from one major version to the other using OCC. Snag is that 8.1.x does block PHP 7 so upgrade fails, 9.X work with PHP 7 but generate error that skipping releases is not supported.

Is there a way of manually export and re-import data after fresh install from version 8.0.16 to current?