8. The participants shall submit periodic reports and a final report to the Board and the Commission on the results from the interoperability regulatory sandboxes, including good practices, lessons learnt, security measures and recommendations on their operation and, where relevant, on the development of this Regulation and other Union law supervised within the interoperability regulatory sandbox. The Board shall issue an opinion to the Commission on the outcome of the interoperability regulatory sandbox, specifying, where applicable, the actions needed to implement new interoperability solutions to promote the cross-border interoperability of trans-European digital public services.