Apple will reportedly use a custom version of Gemini to power the new Siri
PositiveTechnology

Apple is set to enhance its Siri voice assistant by integrating a custom version of Gemini, a move that could significantly improve user experience. This upgrade is important as it reflects Apple's commitment to innovation and staying competitive in the AI space, potentially making Siri more intuitive and responsive to user needs.
— via World Pulse Now AI Editorial System