No breaks intermittent. No

My friends 07 Prius with 210k miles. The other day he started driving the car on couple times wouldn't pull off and the traction control light was coming on without a reason. No spinning tires just dry weather and starting to drive. It went away and later when driving Suddenly lost all the break pressure in the pedal went to the floor. Spun the car on the exit luckily without consequences. The brake fluid in the reservoir is full and there are no leaks anywhere in the brake system. The car always had the two codes p0441 for evap leak and the p0455 (just maybe the gas cap). Now it has a code p0441 for a downstream sensor. Car drives fine and it regenerates. All the coolants are at normal level. The other thing is once you shut off the car the pump that makes the high pitch buzzing noise now screams a little bit louder and higher pitch. And that's not the brake actuator noise that is sometimes going on. No has appeared at all

I was thinking the abs pump thing is going out but why would the pedal has no pressure? I thought it would still have pressure and will somewhat stops and pedal wont go down to the floor.
Any help is appreciated.