The Ambiq Apollo3 uses 6µA/MHz at 3.3V (so 20µW/MHz), so that's something. You can also use it to charge a capacitor that can provide short bursts of energy so

The Ambiq Apollo3 uses 6µA/MHz at 3.3V (so 20µW/MHz), so that's something. You can also use it to charge a capacitor that can provide short bursts of energy so you can use it for sensors that sleep most of the time, taken a measurement and send some data, then sleep again.