Sustainability and governance of the mGov4EU project are critical for its long-term success, particularly in transforming public services and streamlining administrative processes. The mGov4EU project, aiming to design user-centric solutions and enhance cross-border digital public services, places sustainability and governance at the forefront. This involves meticulous outcomes analysis, focusing on pilots and architecture, considering legal frameworks, stakeholder involvement, financial models, and developmental status. The exploration of cross-border mobile government factors reveals consistent determinants across various typologies, encompassing technology, innovation, public officials, citizens, organisations, institutions, public sector context, and broader environmental factors. The multifaceted influences on digital governance initiatives underscore the complex nature of the mGov4EU project. This chapter delves into the piloting impact assessment, analysing design and execution phases. The assessment is crucial for shaping a sustainability plan, recognising core results requiring sustained focus, and identifying areas for improvement. The GOFA model (Governance, Operations, Finance, and Architecture) and Objectives and Key Results (OKR) methodology are applied for a detailed analysis of project outcomes, ensuring a thorough understanding of challenges and requirements for long-term success. The goal is to establish a robust foundation for sustainability and governance, introducing the GOFA model and OKR analysis to navigate the complex landscape of mGov4EU outcomes. The integrated approach ensures a thorough understanding of challenges and requirements essential for long-term success. Challenges across pilots and architecture are addressed, focusing on stakeholder involvement, take-up, flexibility, and continuity. Co-creation principles are integrated into different project stages, fostering collaboration and engagement with various stakeholders. A transdisciplinary context is integrated into the impact assessment, and the GOFA model is employed for sustainability and governance. The co-creation principle is a recurring theme, engaging stakeholders in ongoing project development and execution. In general, the mGov4EU project, emphasising sustainability and governance, presents a holistic approach to address the complexities of cross-border digital public services, ensuring long-term success and impactful outcomes.