At the German Maritime Museum, the user-centered approach of the digitization department has emerged as a driving force for implementing an open and participatory strategy. The department establishes long-term cooperations with various focus groups and partner institutions. These are particularly valuable for the continuous improvement of our digital infrastructures. At the heart of our participatory work lies a Goal-Directed Design approach, which focuses on understanding user needs and motivations. This approach helps us to maintain clarity in complex and heterogeneous projects and to communicate with non-technical users, enabling them to participate in the discussion of future use scenarios. In such co-creative processes, we have found web-based applications—especially Progressive Web Apps (PWAs)—to be particularly valuable due to their accessibility and flexibility. This paper illustrates our interdisciplinary design-led working process through a case study in school education. Additionally, it explores how the German Maritime Museum as a whole has developed further through increased participation: close transdisciplinary collaboration allows us to embed our practical methodological knowledge across the organization. This consistent commitment to participation is already reshaping the museum, giving it new citizen-centered roles.