Unlock your Chromebook with your Android phone
I apologize for not posting an answer in timely manner, however I'm doing it right now (that's the best I can do); As of now I'm using Google Chrome OS / Version 66.0.3359.43 (Official Build) dev (64-bit) and Pixel, (Phone by Google (1st generation)) w/ Android 8.1.0.

I went ahead and removed my Phone from Chromebook's Bluetooth devices and from Chromebook from Phone's Bluetooth devices, now that everything is tidy widy, you can proceed to next step:

under Settings, expand Screen lock (under People), click on Smart Lock for Chromebook (beta) and follow steps.