No matter how good a smart device may be, it remains useless outside the context of a digital ecosystem. Internet of Things (IoT) environments are possible as long as services and products can interconnect smoothly and exchange data in real time. Therefore, interoperability ranks high in global policy agendas, with the promise of bringing an end to network effects slanted in favour of ecosystem orchestrators. However, recent regulatory initiatives introducing interoperability obligations risk falling short of their intent or even risk generating unintended consequences in the absence of a coherent approach to standardisation. Against this backdrop, focusing on the UK Open Banking experience, this article makes a proposal for workable interoperability in IoT ecosystems aimed at ensuring market contestability without undermining incentives to innovate.