Google changed tactics in 2016 with the launch of the Pixel and Pixel XL. The Nexus brand was gone, and the phones were more expensive. Still, the Pixel turned out to be a fantastic phone. Google kept it around on the Google Store even after the Pixel 2 launched, but now that's over. The first-gen Pixels are gone.
The landing page URL for the 2016 Pixels now redirects to the phone category on the store, and that page includes just two links: the Pixel 2 and accessories for the Pixel 2. The Pixel had a good run, and it probably wasn't selling a lot of units. Google knocked a bit off the price of the first-gen phone after the Pixel 2 launched, but it still started at $549. The Pixel 2 was just $100 more.
If you still want to pick up a first-generation Pixel, it shouldn't be hard to find one on eBay or some other retailer. You just can't buy it directly from Google.
- Google Store