F1 nerd here. The turbo and compressor are still mechanically linked. Mercedes pioneered this eras engine with the exchaust side and intake side on opposite end

F1 nerd here. The turbo and compressor are still mechanically linked. Mercedes pioneered this eras engine with the exchaust side and intake side on opposite ends of the engine, and still managed to connect them with a shaft. If you know anything about turbos, think about this for a moment. They have mechanically connected two components with a shaft along the entirety of the engine block, rotating with 100.000 rpm. That is amazing. They have an electical motor on the same shaft that will either harvest or keep the turbo spinning. This beautiful arrangement means that they design the turbo to extract as much energy as posible, and control it with the motor, rather than rely exclusively on the wastegate. This as you state, means that they can recoupe quite a bit of extra energy. I would not be surprised if we see non turbo charged engines, with an exhaust energy recovery system for hybrid engines.