The will likely be using Phoenix: https://www.dataport.de/about-phoenix/ The German government developed a fully free and open source solution that is quite similar (consisting of Nextcloud, jitsi, Collabora etc.) and can be deployed using Kubernetes: https://gitlab.opencode.de/bmi/opendesk
Instead of everyone rolling their own subvariant of Nextcloud, Matrix, LibreOffice etc, imagine if there was an EU mandate set up and some serious money was budgeted to it.
You’d get a triple multiplier of more budget, less duplication of effort, and a self-reinforcing cycle where more use means the product becomes better through contribs which makes use even more attractive.