I think you are going to have trouble getting an external grabbing bolt remover inside the pulley.
My best suggestion is to load the car on a trailer and take it to a TIG welder. The TIG is hot and very precise heat to attach a longer, larger bolt to the damaged one so you can get a big wrench on it from beyond the pulley. A MIG may work, but the guys who have both will use the TIG always.
The added benefit of a TIG is you will thermal cycle the bolt which will help crack it loose.
Before you light up the welder, be sure to disconnect the ECM or any other electronic device. Welders can induce damaging stray high voltage even when the battery is disconnected.
I would not try to hand drill the hardened bolt. If you slip off you will damage the crank. No need to cut up the pulley with the TIG technique.
As you probably know, or tried, these bolts are easier to remove with an impact. Of course hand torque them to install.
Good Luck! I’m impressed you are among the few to tackle wrenching, especially in your neighborhood 😉
