The European Commission has set an ambitious goal to double the share of electronic component design and production done in Europe by 2030. As one significant contribution to achieve this goal, academic and industrial stakeholders focus on developing and expanding an open-source RISC-V ecosystem as a strategic investment for Europe. The industry-initiated TRISTAN project aims to extend, expand, and industrialise the European RISC-V ecosystem to compete with existing commercial alternatives. The project aims to leverage the Open-Source community to increase productivity and quality. In addition, the broad-based international consortium will expose a large number of engineers to RISC-V technology, which will further promote adoption and ensure that this ecosystem becomes a sovereign European alternative to existing industrial standards. The national consortium in Austria is making a significant contribution to TRISTAN, contributing to the ambition to establish Austria as “chip forge” in Europe. The diversity of the partners and their complementary position in the value chain ensure a strong Austrian footprint in TRISTAN and a high impact with regard to dissemination and exploitation. Furthermore, with the intensive cooperation between academic and industrial partners, the open-source aspects are brought into focus just as much as the exploitation interests of the industrial partners. TUG will focus on the development of HW/SW co-design solutions (with industrial partners) for RISC-V ISA custom extensions. TUG will provide solutions from the investigation of the ISA extension through simulation and design space exploration analysis targeting performance, timing and energy use optimizations.