Right now, EU OS is not a project of the European Union. Instead, EU OS is a community-led Proof-of-Concept. This means it is lead by a community of volunteers and enthusisasts.
The project goal is to become a project of the European Commission in the future and use https://code.europa.eu. For this EU OS is in touch with the public administration on member state and EU level. So far, EU OS relies on EU OS · GitLab.