The Slovak Comprehensive Music Database (SKCMDb), supported by a national data sharing space, connects Slovak music libraries, rights holders, and digital platforms through a shared metadata backbone built on open ontologies. Developed within the OpenMusE project, it enables cooperative cataloguing, FAIR-aligned data stewardship, and integration with streaming platforms, print score libraries, and webshop services. Rooted in the Feasibility Study for the Establishment of a European Music Observatory and the Feasibility Study On Promoting Slovak Music In Slovakia & Abroad, this poster traces the steps taken to address metadata fragmentation, shallow documentation depth, and the resulting challenges faced by small- to medium-sized European repertoires. Our system combines open-source components—R, Wikibase, Apache Jena Fuseki, Blazegraph, Sampo-UI, and Reprex’s own open libraries—and applies the European Interoperability Framework together with the Big Data Value Association’s data sharing space model. It demonstrates how collective management organisations, music information centres, libraries, publishers, and labels can collaboratively build more transparent and data-driven music services. The Slovak pilot illustrates how libraries and national music centres can take a central role in a decentralised European Music Observatory that federates with the EU Open Data Portal, Europeana, ECCCH, DARIAH, and Zenodo. This poster accompanies a companion contribution on the Finno-Ugric Data Sharing Space, including the LīvMDb (Livonian Music Database), which explores how smaller regional repertoires can be embedded in broader, multimodal cultural graphs—advancing the vision of a European Music Observatory as a complement to the European Cultural Heritage Cloud.