I think you already answered your own question, granite is the only surface that can take that heat and keep your laptop away from where you iron.

Soapstone is another option. It is highly heat resistant (ancient peoples made cooking pots from it and it was used to house high voltage electrical equipment and wiring) and is nonreactive to chemicals (this is why it's used for science lab tables and you don't need to seal it). It's much softer than granite and is susceptible to scratching, but if it's a utilitarian work surface, whatevs.

I have pyrolav in the kitchen and I slap hot pans right out of the oven on it with no marks or chips.

That pyrolave (enameled lava) looks like it could be a fantastic solution for the questioner as the manufacturer claims it's impervious to heat and acids. (It would be interesting to get a sample and try putting an iron or very hot pot on it to see what happens.)