[chucker]

QNX is the OS that runs on the car's hardware, but it arguably isn't the OS that runs the CarPlay software, much like, if you browse AppleNova on a Mac, OS X is the OS you use to interact with AppleNova, but CentOS (Linux) is the OS that powers the website.

Things like controlling CarPlay using your steering wheel buttons are presumably implemented in QNX (and maybe in other OSes for the car, too), if we understand correctly how it works. But things like the back/forward buttons in a Web browser, too, are implemented in OS X.