The Prius architecture is always terribly described, but it's effectively a differential. Always in mesh, no gears to shift. The speed of the wheels is varied relative to the speed of the ICE by shifting power between generators and motors.
So, to the driver it feels like a CVT with very fast ratio adaptation, but mechanically there's no ratio being varied. It's all fixed gearing, and the variation is done with motor RPMs and torque.
Most all hybrids that operate in series mode, or primarily in series mode.
The Chevy Volt and all current Honda hybrids work this way. The main motor spins the wheels directly at a fixed ratio. The engine primarily operates as a generator. Then they do have a lock up clutch to connect the engine to the wheels when their speeds align at cruise and there is an efficiency gain to be had from eliminating conversion losses. https://youtu.be/QLUIExAnNcE
Also, technically most Toyota hybrids are also fixed ratio, most of them use planetary gears with two electric motors to simulate gear ratios with respect to the engine. It is somewhat confusingly called an eCVT, although the variable part isn’t the gearing, it’s the speed of the motors connected to the gearing. What changes is the relative speeds of MG1/MG2. It’s like a differential in a car, but backwards.
Parallel hybrids are the ones that drive like regular cars. Like Honda IMA, Hyundai’s hybrids, anything labelled “mild” hybrid —- those all have old school transmissions.
So, to the driver it feels like a CVT with very fast ratio adaptation, but mechanically there's no ratio being varied. It's all fixed gearing, and the variation is done with motor RPMs and torque.