I came across an interesting Indiegogo project called the castAway Case and while it’s not the standalone Chrome OS phone that some might want, it’s the closest I’ve seen yet. Essentially, castAway is a smartphone case that adds a second connected display running Chromium OS.

The idea here is similar to the currently available LG G8X ThinQ Dual-Screen phone: That device has an optional second screen built-in to the phone case. The phone side has all of the smarts and connectivity while the second screen can be used to run other apps from the phone.
The castAway case is also a second display for your Android or iOS phone but it differs from the LG option in that it’s not just a dumb display. Instead, it has its own processor, the OP1 used in the Acer Chromebook Tab 10, 4 GB of memory, it’s own battery and both Bluetooth and Wi-Fi radios. There’s no cellular radio in the castAway, but it can tether to the primary phone for web access.
What’s most interesting here is that the castAway is running Chromium OS; essentially Chrome OS without the native Google integrations. So you get the Chrome experience minus Google out of the box on either a 5.8 or 6.3-inch touchscreen display.
How well will that work with the connected phone? Not quite as well as the LG dual-screen option, mainly because the castAway uses two different software platforms: Android or iOS on the one side and Chromium OS on the other. There is some integration between the two using included software called MultiTask+, but we’ll have to see how well that works.
Keep in mind that the Chromium OS device is magnetically attached to your smartphone so it can be used as a standalone Chrome-like tablet of sorts. That might be handy since the castAway will have connectivity to the web or your smartphone while within a certain range. Here’s a look at that use case from an early-on 7-inch prototype for the project.
If the castAway case sounds appealing, you can back it with an early bird special of either $129 or $139 depending on the display size. Full retail pricing is expected to be $249 or $269 when, and if, the project delivers in May.