If the EU had own large corporate hyperscalers that would be an issue there for the EU?

Yes it would still. Which is why I think the process is misguided. I mean look at Hungary which was a near miss. It needs to be resilient to state failure as well.

This means that the entire idea of a corporate EU spanning hyperscaler should never exist.

State failure is something the Europeans have experience in dealing with.

That aside: how much would that cost in lost economies of scale?