I don’t really get hybrid drives for aircraft, if you are going to have electric drive for a propeller you need a generator of some kind which is is going to weigh more than any gear box. In addition the current bypass turbine is compact, fairly light and uses the thrust from the turbine as well as the fan, the power source in any other position would provide less thrust and be no more efficient
There are plenty of examples of electric drives in locomotives, heavy plant and tractors using massive Diesel engines where weight is not an issue and mechanical transmission impractical, for large aircraft weight is a big issue and only a turbine gives an acceptable power to weight ratio. For light aircraft a piston engine could drive a generator to charge the battery to power the electric motor drive, replacing the direct drive propeller but as we have seen in cars fuel economy gains are difficult to achieve, the main advantage is less city pollution.
Any hybrid aircraft would need to carry batteries + fuel + piston engine + generator + electric motor, it will be interesting to see what payload is left.