After you sign in, you can install a Shortcut that will allow you to
use ChatGPT from Siri by saying "Hey Siri, question." See
video tutorial.
Sample conversation
User:Hey Siri, questionSiri:What's the question?User:Tell me a cool fact about the planetsSiri:Did you know that Venus is the only planet in our solar system
that rotates clockwise? This phenomenon is known as retrograde
rotation and it's quite unique!