I have an idea for a propellantless vehicle if this theory works, which is a pair of wheels on the same plane (axes of the wheels are parallel to each other) attached to each other and each driven by motors that spin them in opposite directions. I hypothesize that arrangement would allow this vehicle to both translate and rotate in spacetime on this plane, by adjusting the speed and direction of each wheel, and there's no propellant involved, so the motors could be powered with solar cells. To make one that can move around in spacetime in 3 (spatial) dimensions, just add a third wheel, and mount each wheel in planes in such an arrangement that makes them 120 degrees out of phase relative to each other.

The idea is that at the center of this vehicle, spacetime is compressed, and the points on the wheels closest to each other are moving through a distorted spacetime field relative to the spacetime field where the points on the wheels farthest away from each other.