Even if they didn't do it first, at least Apple has a plausible claim for why they did it -- the iPhone screen goes all the way to the bottom edge. The Pixel doesn't have that restriction, so why do a notch?
The thing that really irritates me about a notch on the Pixel (or any other Android phone) is that it's much more intrusive. Not just taller (though it is), but on iOS notifications are not handled the same way, so you're not really giving much of anything up with the notch. But on Android, notifications frequently take the entire top of the screen -- right where that notch is. Seems unnecessarily clumsy.
Regardless of what happens on the bottom, without the top notch the total screen area is smaller; with it it is larger. Isn't having more total screen area a plausible enough reason to do it?
The first phone to have the notch was the Essential Phone, and the notch is much smaller than the iPhone (https://www.essential.com/#introduction). The pixel does have a dual camera that the iPhone does not have. And it's deeper, where the iPhone is wider. They seem to almost have the same footprint, but I could be wrong.
The thing that really irritates me about a notch on the Pixel (or any other Android phone) is that it's much more intrusive. Not just taller (though it is), but on iOS notifications are not handled the same way, so you're not really giving much of anything up with the notch. But on Android, notifications frequently take the entire top of the screen -- right where that notch is. Seems unnecessarily clumsy.