The Prius-style Toyota hybrid transmissions are actually much simpler than in an ordinary car. The planetary gear system allows engine RPM to be decoupled from the wheel rotation, with the motor/generator taking up the slack. There is no clutch or changing gear ratio.
Once I fully grokked how the Toyota hybrid transmission worked it kind of blew my mind.
It’s so simple, but so adaptable, and far simpler than any other transmission I’ve seen in a car.