For years, Google's Nexus line could be counted on for one thing, an unlockable bootloader. While carriers have occasionally had limited freedom to defile customize certain models sold through their service, owners were at least free to either modify the stock software or completely replace it with custom builds.
It goes without saying people were more than a little disheartened to learn Google's second attempt to team up with US carrier Verizon lead to yet another disappointing result: the Google Pixels sold through VZW have non-unlockable bootloaders. In fact, there are at least two carriers selling non-unlockable Pixels. The other is EE Limited (formerly Everything Everywhere) in the UK.
If you ended up buying one of these developer-unfriendly models, you might be looking for a way to restore their full range of function, and now you can. Justin Case (jcase) and beaups, possibly best known for their Sunshine unlock service, have discovered a method to force the Pixel's bootloader into an unlockable state, allowing it to be treated just like the models sold direct from Google. They've developed a free tool called dePixel8 that makes the process quick and fairly straight-forward.
Full instructions and a download link are available on theroot.ninja site, but the steps basically involve copying the dePixel8 tool over to your Pixel, changing its permissions to be executable, and then running it. The device will restart to the bootloader where fastboot can be used to issue the oem unlock command. Just like a normal unlock, the user data partition will have to be wiped.
It's important to note that the method used by dePixel8 to enable unlocking will surely be fixed soon, most likely with the November security patches, due out on the 7th (first Monday of the month). In other words, if you want to unlock your Pixel, do it sooner rather than later because this tool may not be an option after the next update.
Again, the tool is completely free (and without warranty), but jcase and beaups encourage users to either purchase unlocks for other supported devices with their Sunshine unlock tool or make a donation to the Make-A-Wish Foundation.