Municipalities are increasingly expected to function as data-driven organizations while simultaneously providing access to data for research, innovation, and the creation of public value. Despite having large volumes of potentially high-value data, municipalities face significant barriers to data sharing due to legal fragmentation, vendor lock-in, and limited organizational capacity. This position paper presents the MUNDAT use case from the EU-funded DataPACT project, in which Trondheim Municipality, together with technology providers, explores how a federated “single-window” data request and delivery pipeline can address these challenges. Today, municipal data requests are often handled ad-hoc and are labor-intensive, leading to inconsistent compliance assessments, high resource consumption, and increased legal risk. MUNDAT reframes the challenge not as a lack of data, but as a lack of an efficient infrastructure between municipal operations and regulatory requirements. The paper examines two contrasting data sharing cases: HR sick leave data, where legal and ethical constraints dominate, and infrastructure IoT data, where vendor lock-in, security, and critical infrastructure concerns prevail. By combining automated legal assessment, policy enforcement, and technical data pipelines, the proposed single-window approach aims to provide a lawful, scalable, and reusable data sharing infrastructure, while supporting consistent, transparent, and auditable compliance with applicable legal and ethical requirements.