The virtual integration of geographically distributed RI for joint experiments in the domain of power and energy systems poses numerous challenges, particularly in terms of tool compatibility and user-friendliness. To address some of these challenges, this work presents the development and implementation of a laboratory-based middleware and data exchange service as part of the H2020 ERIGrid 2.0 project. The middleware comprises a suite of shared software tools and services designed to seamlessly integrate RIs including transport protocols as well as interface semantics. Specifically, this work details the development of a simplified and standardised interface known as the UAPI. It eliminates the need for users to grapple with the diverse intricacies of each individual RI, offering instead a tool-agnostic and standardised interface for conducting joint experiments. The work also presents and discusses the results of a real-world case study of a geographically distributed, sector-coupling experiment conducted between laboratories in Denmark, Greece, Italy, Netherlands, and Norway utilising the developed middleware.@en