You can. Buy or solder a SuzyQable[1] to unlock the firmware, flash MrChromebox's coreboot build[2], and install linux on it. I'm typing this message right now on my pixelbook running Arch Linux. So far the only problems I have with it is the audio does not work and I can't change screen brightness. The screen brightness is because linux refuses to use DPCD when the PWM line is connected. On the pixelbook the PWM line is connected but doesn't do anything. There are kernel patches you can apply to force DPCD but personally I'm just hoping someone eventually commits a fix upstream to let us toggle it.
