Those original Chromebook Pixels were awesome machines.
I wish they'd had open bootloaders, but I seem to recall you had to keep it in developer mode which required a nag screen, or something along those lines, if you wanted to run your own OS on it.
You can easily remove the nag screen by opening the device and unscrewing a screw and running coreboot with SeaBIOS. Pretty neat security approach (not too hard to do, not too easy for a layman to fall for instructions to self-compromise). I have two that work just fine today.