Because I have mentioned Mavic’s original electronic shifting setup, ZAP, a few times, figured I should link through to some recent photos I saw of the gear. I’m always brining it up because it demonstrates the flexibility of an e-shifting setup that did not rely on dedicated shift/brake levers for actuation. Instead, one could use the little toggle button controller anywhere on the bars, freeing the rider to pick whichever brake levers they preferred regardless of how they connected to the shifting.
The actuator button:
The rear derailleur (which was powered by the motion of the chain through the pulleys, I believe):