This document describes use cases, data exchange and interoperability requirements, demonstration and KPI-based validation approaches, and grid observability considerations related to the implementation of peer-to-peer (P2P) energy trading and the assessment of its impact at distribution grid level. The document draws on the implementation experience of the Horizon Europe projects FEDECOM and OPENTUNITY. It provides implementation guidance for distribution system operators (DSOs), energy community coordinators, solution providers (including aggregators, IT integrators, and technology vendors), and public authorities involved in the deployment or assessment of decentralised energy trading schemes.