someone needs to measure the heat coming from the cooktop surface to know whether it can support powdercoating. household stoves, ovens and burner grates are all porcelain covered (aka stove enamel). porcelain is a baked on finish similar to powdercoat but it can withstand higher temps.
chrome is used as a cooktop surface or even as a griddle surface on vintage stoves - griddles only get up to about 400-425 degrees though.
that's about all i can add from my stove and motorscooter restoration knowledge
An engine only gets to about 220ish degrees at its hottest (the coolant thermostat is set to 180F usually).. That's the right range anyway... That's why people can powder coat valve covers and not have to use high-heat paint
on the block... Headers and exhaust manifolds, however, can get up to 1200F which is why those parts get ceramic coated. Powder coating is really just tiny tiny plastic beads (dust basically) that are sprayed on to the item in question. The item is connected to a high voltage electrical
source and the gun is the other side. The dust is attracted to the item due to electrostatic forces. The item is then baked at 400F-ish to melt the plastic beads together to result in the powdercoat finish you admire...
The flame from a propane
burner is much much hotter than 400F and so will burn the plastic when it comes into contact with it. Not to mention the heat of the flame reflected back off the bottom of your kettle onto the plastic.
Powder Coating a stove top is not the right answer.
I don't know what colors, if any, they can do with ceramic coating but that would be the right answer, as far as that technology goes.
Frankly, I think you can have your stovetop chromed for about the same amount of money as powder coating...