This will build the default output for your Acer Chromebook 311.
$ nix-build --argstr device acer-juniper -A outputs.default
The default output is a disk-image that can be written on a storage media that your device can boot from.
This one is annoying to get started currently. Without a full Mobile NixOS build, you will need to fill in some gaps manually.
The upstream documentation about the disk format may help shed some light in understanding how these devices boot.
One of the important thing to realise is that you will likely need to
image to a storage media, either external or internal.
kpart output can be used to build only the stage-1, which is helpful for
updating the kernel and the stage-1 boot program.
$ nix-build --argstr device acer-juniper -A outputs.kpart
This can be `dd’d over the first partition on an existing storage media containing a Mobile NixOS installation.
(No device-specific notes available)