> That certainly makes the mechanics complicated, an array of such pins is not exactly off the shelf today either, I think?

A solenoid is just a pin with an electro magnet wire wrapped around, put a spring on the pin to pull it back into the electro magnet and when you turn the magnet on it should vibrate.

A 100x100 grid of solenoids should cost under $100 they are fairly cheap, you might even be able to use a grid of wires and pins so they are addressable.