It's great they open source a lot of their stuff, but just because you're big enough as a company to rewrite {component of build chain} for yourselves... doesn't mean you should.
Caveat: I know parts of Google are awesome with contributions and using standards.
edit: GPL -> AGPL
Purchased a Google WiFi for example and the license agreement is pages long of using open source software.
https://support.google.com/wifi/answer/7359345?hl=en
Google uses the Linux kernel for everything. From Google Home to Chromecast to their cloud and Android and ChromeOS.
Only now working on their own kernel, Zircon but suspect just experimentation.
Google tends to use off the shelve if something exist to use. They tend to focus on new things.
Another great example is using Intel processors but did the TPUs as nothing available to meet their needs.
Then we get speech to text using a NN at 16k samples a second at a reasonable cost.