I’m talking about the iPhone.
It's not deeply integrated into the iOS by any normal definition. It's just shipped together.
Btw, maybe related, on iOS I have "app privacy report" enabled, to show me a list of apps and the recent entitlements they used. Every Apple app, even those that don't need access to them, is shown as having recently accessed my Contacts. I find this weird. Anyone know why they do that? e.g. I've never even used the Health app and yet it's accessing my Contacts for some reason.