Euro-Office: sovereign in name only, or in reality too?

The announcement of the Euro-Office is welcome news. The coalition is credible, the governance is sound and the timing is perfect. Europe needs office software, and I am delighted to see such significant players allocating resources to make it happen.
However, we have a question. It is not meant to be hostile, but it is the only question that matters.

What is the native document format of Euro-Office?

https://blog.documentfoundation.org/blog/2026/04/01/euro-office/