And I'd argue there's really no reason it couldn't be much more complicated than a rheostat and a static circuit to get the desired curve.
I can't find the actual circuitry, but I'd not be surprised if that was what the EV1 did in the 90s.
Software adds flexibility, it isn't a necessity.
The gas pedal on an EV isn't connected to a passive rheostat gating the entire power output of the vehicle.
It's a low-voltage sensor. A capacitor can swallow a transient of a 0.1v signal bursting to 5v for ten milliseconds, and then software converts it into whatever "sport mode acceleration curve" the marketing department calls for.