The only ebike I tried with an e-cvt only worked if power was on. Without power you rotate the crank but that’s all. For a city bike this is an advantage, being some kind an anti-theft device
What’s worth to mention is that both electric motors will provide torque to the chainring/pulley/rear wheel. If one motor would have only been used for changing the gear ratio, it would not be a very efficient system. In this respect, not much energy is wasted when varying transmission ratio. Even if the system is rather straightforward mechanically speaking, controlling it for proper feel/response is not something so simple. I would definitely try a eMTB with E-cvt to satisfy my curiosity.