Libre Office is maintained by The Document Foundation which is based in Germany. So from a governance point of view it’s already a European hosted open source project.

Also for online collaboration platforms, Libre Office isn’t really a good option. It is an old, sprawling codebase which doesn’t lend itself to being ported to being a server based collaborative platform. It has actually been done but hasn’t flourished, hence alternatives like OnlyOffice.

Also this is more about OnlyOffice’s issues - the lack of transparancy and true collaboration with contributors, the proprietary code used for mobile apps, and it being based in Russia which is geopolitically problematic especially if part of the idea is “Euro sovereignty”