Ask HN: What does open source from top tech companies say about them?

In my eyes, Google and Facebook seem to be competing in open source, with Flutter vs RN/ react, Tensorflow vs PyTorch, Kubernetes, Go, Fresco and so much more. I don't notice Amazon, Apple or Microsoft (although MS definitely do have some, like Typescript and VScode, the volume doesn't compare). Does lack of open source hint at a place that is moving slower, is less developer driven and more management driven, and would be unlikely to grow in the future or has fewer growth opportunities for developers (relatively speaking)?

Alternatively, it's just because Google and Facebook are more consumer focused and I've systematically found their contributions, where as Microsoft and AWS are more enterprise.

Great, simple OSS catalogs: https://opensource.facebook.com/projects https://opensource.google/projects/explore/featured

I mean, just look at the hideous UI at https://opensource.apple.com/ Do they not care? https://opensource.microsoft.com/?sort=Stars&keyword=&tag=

Anyway, does open source give away any information about these companies. I'm trying to understand how to pick companies for employment/ graduating in a few months.