My only experience trying to build ChromeOS was for "Container-Optimized OS" which doesn't have nearly the same "random binary blobs" problem as trying to build for a piece of consumer hardware
Keep in mind, Google's reputation among hackers has dropped a lot in recent years. Trying out an operating system where the core premise was "you spend 95% of your time on your netbook just in a browser, why not optimize for that and strip away the rest" was an intriguing proposal. This was back when doing things in web apps instead of desktop apps was new and forward-thinking, not totally overdone the way it is now.
For ARM chromebooks I'm only aware of https://archlinuxarm.org/ and that's still pretty patchy; I hope that something comes together (or that it already exists and I just haven't found it yet).