A comprehensive understanding of rail user and system requirements is the foundation for the development of hybrid virtualized testing. Moreover, a specifically tailored framework for GNSS-based railway localization solutions within the European Rail Traffic Management System (ERTMS) is an important need for certification. The HyVICE (Hybrid Virtualized Certification Environment) platform, developed by the VICE4RAIL consortium, is envisaged as a comprehensive environment combining laboratory simulations and on-field testing to certify GNSS-based train positioning systems according to Safety Integrity Level 4 (SIL4), which is a safety need in railway transports. Additionally, the system must be resilient to various threats that may occur during operation, including intentional jamming and signal spoofing or meaconing attacks. Analysing European railway regulations and standards in the context of safety assessment and certification processes is a second step for the technical identification of needs corresponding to the complex certification landscape that GNSS-based solutions must tackle. As integrating satellite technology into the safety chain of railway operations poses significant technical and regulatory challenges, the third step is to develop a certification plan based on the initial outcomes. Finally, the former will consolidate the certification process for the targeted HyVICE test platform by incorporating both insights and processes previously identified.