Malibu 2005 noise while braking that isn't brakes?

When I brake I get a rhythmic noise that starts like a quiet chirp and by the time I have completely put the brake pedal down it sounds like a loud grinding noise. It is a rhythmic pulsing noise, not continuous.
I recently got new rear drum brakes, and 2 garages said my front brakes were fine. One guy said it could be the wheel bearing but I looked online and it says that happens when you accelerate, not when you brake.
It only happens when I brake at relatively low speeds. In other words if I’m on the hiway and brake to slow down from 70 to 60 or 40 to 30, it won’t happen. I also feel vibration in the brake pedal, but only when I have almost completely stopped. Anybody have a clue?

I had a similar problem, not the wobble but the chirping sound, took it to a brake specialist and it turned out the inner pads were worn to the bone but not the outer. Perhaps get them to inspect all 4 pads, and sounds like rotors as far as wobble. Are your front wheels or one of them especially hot after driving a while? could be a sticking caliper causing brake fade.