How to connect to aws iot core without authentication

This is not possible nor advisable. The closest would be using an unauthenticated Amazon Cognito identity. See:

https://docs.aws.amazon.com/iot/latest/developerguide/cognito-identities.html https://docs.aws.amazon.com/location/latest/developerguide/authenticating-using-cognito.html

What's the use case for this?