With the commissioning of large machines like the ITER tokamak, controlled fusion is poised to make huge step forward towards mastering the energy of the stars for a civil usage. The steady international progress regarding the achieved fusion performance gain – the ratio of the generated fusion power over the injected power – relies on our ability to understand and predict the turbulent transport and confinement properties of the plasma. Core transport studies in tokamak plasmas have now reached maturity with the development of state-of-the-art first-principle-based codes, using the 5-dimensional gyrokinetic description. However, despite their numerous successes to date, their predictive capabilities are still constrained with respect to the energy content in particular in optimized discharges. Challenging this gap requires pushing gyrokinetic modelling towards the edge region of the container vessel, and as far as possible addressing edge and core transport on an equal footing, which makes nonlinear simulations mandatory. In EoCoE-II the goal for the fusion team is to bridge the gap between gyrokinetic core transport modelling and edge plasma physics for reliable predictions of fusion performance, which will require a number of numerical and physics bottlenecks to be overcome. The objective is to develop a new numerical tool to address the core edge issue, which will consist of refactoring and rewriting the flagship gyrokinetic code Gysela (its new name will be GyselaX), targeting the disruptive use of billions of computing cores expected in exascale-class supercomputers. This will be complemented by the upgrade of companion codes Tokam3X/Soledge2D, and GENE, to provide critical inputs both regarding numerical developments and physics issues.