>Also, surprisingly, both Amazon and Apple aren't really known for prolific OSS contributions according to their size.
The amzn [0], aws[1], and awslabs[2] github pages combined have 500+ repositories. AWS contributed back to the Linux kernel[3] and Xen[4] for Spectre and Meltdown related things. There are other projects large enough that they are under their own page, like Blox[5]. There's been plenty of others I've stumbled across randomly - this list isn't meant to be exhaustive or even close to it, but just what I personally can think of off the top of my head.
(Disclaimer: I work at AWS, and contribute to an open source project as a portion of my job. This isn't an official post or anything of that nature, and opinions expressed are my own - I'm just a random dude that wants to share that a lot of cool open source stuff happens at Amazon/AWS!)