GNSS is amongst the “game-changing” technologies for future digital and automated rail operations, acknowledged in a 2015 report from the European Union Agency for Railways (ERA) on the longer-term perspective for the evolution of the European Rail Traffic Management System (ERTMS) and the EU Parliament in its adopted report on railway safety and signalling from July 2021 also calls for a joint effort towards the introduction of GNSS in ERTMS. Three major railway operators in Europe – DBN, SBB and SNCF – endorse and support the efforts of the EU Parliament and propose a follow-up-project to the "Certifiable Localization Unit with GNSS in the railway environment” (CLUG) project to demonstrate the technological readiness of the CLUG Localisation On-Board (LOC-OB) System. In CLUG 2.0 (CLUG Demonstration of Readiness for Rail), the system architecture aims to complement the existing European Train Control System (ETCS) odometry system by using GNSS to enable absolute safe train positioning whilst also transforming the way of train localisation is done today by demonstrating a GNSS-based multi-sensor fusion architecture. To ensure that an enhanced on-board localization in ERTMS/ETCS using GNSS is interoperable, the technological readiness of the LOC-OB System shall be demonstrated in CLUG 2.0. To achieve its objectives, the consortium continues the work started in the first CLUG project, by improving the design of the safe functional architecture and validating it against the requirements defined by the operators. Ultimately, all thanks to an improved LOC-OB System for ERTMS, benefits such as increasing the line capacity, reducing headways between trains, reducing expenditure for rail infrastructure rollout can help reduce emissions, and accelerate the adoption of sustainable and smart mobility solutions that revolve around rail. LOC-OB can make rail transport more attractive, enhance the competitiveness of rail for citizens and businesses.