According to Best Car, which predicted the GR Corolla back in 2020, Toyota plans to introduce a peppy Prius some time between late 2023 and Spring 2024. Tentatively referred to as a GRMN model (technically above the GR level), this Prius will reportedly get an improved unibody, with extra spot welds and industrial adhesives to stiffen the GA-C chassis it shares with the GR Corolla. It'll also gain improved brakes, suspension, and an exclusive interior finish that you'd expect of a GR model.
What Toyota will do for the GR Prius's powertrain isn't known, but Best Car is certain that it'll be based on the plug-in hybrid model, which we know as the Prius Prime. It sounds like there are doubts about the tuning potential of its naturally aspirated, Atkinson-cycle 2.0-liter four-cylinder, so what will power it remains uncertain. Even a modest power bump would put it in Subaru WRX territory though, all while returning better gas mileage and looking far better.