Probably no one, but there is nothing preventing from enthusiasts from hooking an electric drive motor up to a traditional manual transmission just to be perverse. I would.
What would the manual transmission do? Unless you literally mean it doesn’t impact the cars driving and is just there for you to move around. Electric vehicles are not changing gears, so there are no gears to hook up a manual transmission to
It would give you a manual transmission driving experience. Nothing more.
(There are no gears in an internal combustion engine, either. At least not in the context you’re thinking of. The gears are in the transmission. That’s why anyone in the Commonwealth calls it a “gearbox.”)