Google vs Amazon
Google's decision to partner with these companies and others stands in contrast to Amazon's approach. Bezos's firm has launched cloud services that compete with MongoDB and Elasticsearch without cutting them in on the revenue, for example.
Amazon is parasitizing even at Google's own Android afaik, how should they won't on "regular" open source then? e.g. for comparision, "Google Summer of Code" is small (mostly PR!) project for company of that scale ("do not evil" hell yes sure), but still: at least it exists. Nothing similar at Amazon afaik.
btw, I think that "Google Cloud partnership" is (or will be) related to Stadia project.