It’s readily available as regular old nail polish remover

I use a heat gun to get the filament just soft enough , then use tweezers to pull off big chunks. A vice helps here, you can clamp the heat block while you’re heating, then use pliers or a wrench to unscrew the heatbreak and the nozzle. Once the parts are separated, you can drop the parts in a glass jar of acetone, and that will break down the filament so you can get the rest off with a brass wire brush. Just don’t dunk the thermal sensor or heater element in the acetone. The metal parts will be fine, but the insulation on the wires could be damaged depending on composition. I’ve saved and rebuilt several hotends this way - it’s great to not have to be ordering hotend parts all the time. 😁