Experiments have shown that pilot waves would have to travel faster than the speed of light.
My understanding of the experiment is as follows:
Take two entangled photons, beam them up to satellites far away from each other. The satellites have detectors that measure the polarization angle from 0 to 360 degrees. Since entangled photons have opposite polarization you'd expect an inverted V (red line): https://en.wikipedia.org/wiki/Bell%27s_theorem#/media/File:B...
Instead, you get the blue line. Which is weird, because it is basically a cosine curve, and implies that the photons are able to determine the relative angle of the detectors. The crazy part is that this curve still holds even if those detectors are very far apart and you complete the experiment before any information about the relative angles of the detectors would have time to pass from one detector to the other at the speed of light. This is what implies that a pilot wave would have to move faster than the speed of light.