I was surprised to read that Chromebook use at Google was common for engineers. Even if developing remotely I had assumed they'd opt for the most powerful machine possible.
You have access to an extremely powerful remote workstation that from a UI perspective functions almost identically to a local workstation, via Chrome Remote Desktop. Plus, no one builds things locally, even on that machine. There is a huge, absolutely amazing distributed build system that everyone uses for everything. (Again, Android and Chromium are different.)
So you don't really need a powerful local machine. I held out for a long time--there were a lot of growing pains in the early days. But eventually it got really, really good.
One is a framework called Wiz, which renders the frontend for a bunch of Google web apps. You can imagine that the Wiz team might want to refactor an API, but not have to worry about different apps using different versions. In a monorepo, they can just find all the callsites and update them in the same commit that makes the API change. There's no package.json in google3 - everything builds from HEAD. Therefore, the commit that makes a breaking change is also the commit that fixes the would-be breakage.
This architecture evolved. Google used to use Perforce, which was a common commercial version control system before Git. Google had to figure out how to express the dependencies between packages in the monorepo (which can be in different languages with different build tools). They eventually created Bazel, which expresses those dependencies and orchestrates their build tools.
Build orchestration took a few attempts. Google3 is the third version of the monorepo, that is, the one that uses Bazel for dependency management.
Size has nothing to do with it.
There are many open source projects that are developed in google3.
How is this enforced?
If you need to do development locally, you are either doing something very wrong or extremely specialized.
So there is effectively no motivation to copy the sources over. And because everything is on this distributed file system and built from it in a very bespoke environment, I would imagine (with no inside knowledge at all), that it is easy for auditors to detect when someone starts copying things out.
When it finally failed in the most annoying way possible (the touch screen, which I do not use, started creating phantom clicks in the upper right corner of the display) I went looking for another Chromebook that was light, powerful, and well-built. Finding none, I now use MacBook Air and weep for the time I lose every time it needs an OS update.
FWIW I don't think this is accurate (was kinda true in the 2010s?). I wouldn't be surprised if it's almost easier to get windows laptop than linux one now.
Afterwards I was issued a 12" Pixelbook and it was surprisingly much more usable than I had expected! I could ssh into a Linux box for running builds and tests. Cider worked perfectly. It was snappy enough to serve as a thin client even on a 4K screen.