Europe's significant role in Earth Observation (EO) and climate change studies, epitomized by the Copernicus program, underscores its leadership in this field. Copernicus, part of the Group on Earth Observation (GEO), contributes to improved access and utilization of open EO data for policymaking. Since 2005, GEO has championed the Global Earth Observation System of Systems (GEOSS) to foster integration and interoperability among EO platforms. EuroGEO, Europe's regional GEO contribution, represents the last leg of the EO value chain, but it currently lacks the essential interoperability for comprehensive policy support. This presentation outlines the rationale and progress behind a EuroGEOSS prototype, conceptualized by the European Commission's Joint Research Centre. Focusing on high-priority European policy use cases and addressing identified issues, the prototype will incorporate key elements like a portal, single sign-on, meta-catalog, modularity, and Machine Learning Operations (MLOps). Rather than a standalone platform, EuroGEOSS aims to be a virtual ecosystem, fostering open standards, novel technologies, and collaboration with European communities, ultimately providing scalable interoperable infrastructures. The development of the EuroGEOSS prototype, set to continue until the end of 2024, will document gaps, challenges, and future scenarios, paving the way for operationalization.