If the Air was retina I think it would be a no brainer. But the ability to run Linux and the gorgeous display does make the Pixel quite enticing. Def would get LTE if I were to get a Pixel
Have you considered the 13-inch MacBook Pro with a retina display instead?
The Google Pixel looks like a wonderful piece of hardware, although I have never seen one in person. But it comes with ChromeOS, and then you will have to rely on web-based software, which is something that limits the capabilities of such a great machine. As good as it is, it is not meant to replace a real laptop for the time being.
You can install Linux on it, but there are still several limitations. You will have to deal with the lack of drivers, or drivers which were poorly written. And, although I have not tried, I guess the installation is probably not as straightforward as it should be due to the lack of support.
Yes, the display may be gorgeous, it has a great 3:2 format, a higher pixel density than any other laptop, it is light and looks like great build quality. But the base version comes with only 32 GB of storage, and it costs US$ 1,300. The storage will seriously limit its possibilities). The LTE version, which you are considering, comes with 64 GB (which is still low), but it costs US$ 1,450. Only US$ 50 less than the 13-inch retina MacBook Pro.
The 13-inch retina MacBook Pro comes with a faster processor (2.5 GHz vs. 1.8 GHz of the Pixel), more RAM (8 GB vs. 4 GB of the Pixel), more storage (a 128 GB SSD versus 64 GB of the Pixel), and more connections (the Pixel has only 2 USB 2.0 ports). In addition, it has more battery life. The Pixel has a slightly higher screen resolution (2560x1700 versus 2560x1600 of the Mac), and it is just a little bit lighter (3.35 lbs vs. 3.57 lbs of the Mac). Not too much of a difference. And the MacBook Pro has the advantage of the operating systems: it comes with OS X, and you are able to install Windows or Linux on it, either using BootCamp or a virtual machine. With Pixel, you are limited to ChromeOS and to Linux with (supposedly) poor driver support.
I do not see a point in getting the Pixel, especially the higher-end one, unless you need the 1 TB storage that comes with it. The 13-inch retina MacBook Pro feels like a much better choice in all aspects. Even the Air, without the retina display, looks like a better choice to me. The Pixel is too impractical.