iOS 17.4 code shows Apple may be testing two versions of its Ajax LLM for Siri and comparing their responses to OpenAI's ChatGPT (Chance Miller/9to5Mac)
https://9to5mac.com/2024/01/26/apple-siri-chatgpt-ios-18-development/
http://www.techmeme.com/240126/p25#a240126p25