Turbopump are driven either by a preburner or by an electrical engine (OK this technology is quite new and currently in 2019 only used on the Rutherford engine).
If I understand correctly, using electric turbopump have some pro and cons, namely thrust to weight ratio, throttle precision, startup time, startup complexity, dropped consumable (either battery or propellant), pipes complexity.
My question is: is it possible to use hybrid drive to drive the trubopump? This way we can take advantages of both precision and startup simplicity due to electric drive and thrust to weight ratio and no need to drop battery due to "classic" preburner.