Mine is an iPhone 16 pro max (for reference). I cannot update my Mac in beta as this is my work device.
It worked on my iPad with fr-FR. And since Siri language syncs across devices, AI got disabled on my Studio and MBA because it was set to fr-CA. Set Sequoia language to fr-FR to match with Siri, and boom macOS started downloading AI. So much work to make this work…!