No other company in the world has workloads that match Google's. So there are two options. You can spend a shitload of money making GCP actually work for the ridiculous needs of google3 applications and then actually get everybody to use GCP rather that using borg directly or you can not spend that money building all the infrastructure to do things that borg already does and has zero external customers.
Turns out the latter is attractive.
What Google does now is just not rev the version in any repo paths. This is true of several projects that previously had versions included in the path. Now all versioning is handled separately.
Motorola is interesting, but considering it was less than a year in Google and more focussed on hardware development probably also not fully integrated and one could argue whether Google acquired it only for the patents they kept when selling to Lenovo.
John Hanke in contrast built Maps and related things after being acquired and only after a few years moved to build Niantic, where at least Ingress was developed fully inside Google (but apparently not fully in Google stack, but so that they could transition to Google Cloud)
But yeah, good examples!
They bought it, stripped out the things they wanted to keep, then spun it back out.