This paper’s objective is to provide an overview of available sustainability Key Performance Indicators (KPIs) for the Information and Communications Technology (ICT) industry and their applicability to 6G ecosystem components such as the Radio Access Network (RAN), Core Network (CN), cloud and edge data centers, end user communications devices, and supply chain and manufacturing. Furthermore, this paper identifies areas of potential research to develop a harmonized set of sustainability KPIs for benchmarking of the 6G ecosystem components.