goddammit. i found the Correct Bicycle, at long last. Pinion has come up with an "MGU" (Motor Gearbox Unit), which integrates an electric motor and gearbox transmission into a unitary module. no hub motor, no internally geared hub, no derailleur. they're not available in the US yet and probably won't be until late 2024 at the earliest.
gearbox bicycles have existed for some time, and Pinion already supported ebikes with gearboxes, but they were all hub-motor bikes, which adds unsprung weight.
they work with both belts and chains. if a bike with an MGU uses a belt for final drive, the only maintenance you have to do on the drivetrain is change the gearbox oil once every 10,000 km.
this pushes the same buttons in my head as they idea of a 3D printer made with DC servomotors and closed-loop control
there is one downside: all the bikes equipped with this seem to be approximately the same price as a motorcycle
