Also, the general guidance for someone who thinks their brakes are failing is to pump them to try to build pressure. In this case that guidance is the exact op

Also, the general guidance for someone who thinks their brakes are failing is to pump them to try to build pressure. In this case that guidance is the exact opposite of what you should do. The guidance is for a different but more common failure mode: brake line rupture. The correct solution to a runaway engine is to slap the car into neutral and then apply brakes and pull over if necessary. But that's not something most driving schools teach nor is it something your average person will practice.