I ride a bicycle, and I deliberately mount the rear light directly at the eye level of typical sedans and SUVs. It's not connected to the brakes, but I find that having the light pulse is enough.
I've got the rear flasher on my road bike tucked as high under the seat as it can get, but even with a large frame bike and relaxed commuting (non-aero) posture I'm shorter than the hood lots of full-size SUVs and pickups, much less the seat.
I agree with the other commenter that a 360 cam on top of the helmet has been the most important thing for deterring tailgating and road rage. I've added reflective tape on the frame, the blinking blinking lights under the seat, a headlight on the handlebars and a headlamp with front white and rear red light, and my backpack has a nearly fluorescent neon green cover. Those all help reduce the "Oops, didn't see you there while looking at my phone" close calls, but do nothing to reduce intentional harassment - that's the function of the camera.
[1] https://www.rivbike.com/products/dyno-rack-light?srsltid=Afm...
That sounds much simpler, cheaper, and reliable than "detect changes in the frequency of the wheel rotation".
Also, it works like a car's brake lights, which drivers are accustomed to, rather than "start pulsing when you decelerate", which is when you stop pedaling (unless going downhill).