The nice thing about Apple owning the whole stack is the color management is pretty decent. Really good for testing your stuff to see how it would look if everyone had calibrated displays with the correct settings all the way through the entire software stack.

I keep a janky 10 year old display hooked up so I can drag my content over to it and see how bad it's going to look on everyone else's systems.

The other trick they have is really good ambient lighting compensation. Google just added something similar to the Pixel series, but it's not quite as good as Apple's implementation. AFAIK Apple have custom driver ICs and panels, which probably gives them way more control.