I’m surprised your kettle is only 1000W. You should be able to find a 1500W one. (The max power possible on a 15A circuit is higher, but I believe 1500W is the maximum permitted “continuous” power draw, and seems to be the typical maximum for heating appliances.)
As you say, if the circuit is shared, you may not be able to draw the max, but kitchen counter circuits are required to be separate from the rest of the house, so if you’re not running other 120V kitchen appliances at the same time, you should have the full power of the circuit.
I’m surprised your kettle is only 1000W. You should be able to find a 1500W one. (The max power possible on a 15A circuit is higher, but I believe 1500W is the maximum permitted “continuous” power draw, and seems to be the typical maximum for heating appliances.)
As you say, if the circuit is shared, you may not be able to draw the max, but kitchen counter circuits are required to be separate from the rest of the house, so if you’re not running other 120V kitchen appliances at the same time, you should have the full power of the circuit.