I don't even work at FAANG but even we have our own in-house grown compute platforms with layers and layers of abstractions and enormous complexity which were b

I don't even work at FAANG but even we have our own in-house grown compute platforms with layers and layers of abstractions and enormous complexity which were built over several years by hundreds of engineers. These don't resemble public cloud or open source solutions at all, ideas are similar at best. You can have a lot of real world small company knowledge but the moment you walk through the door this experience is worthless, all that counts is how fast you can adapt and how good your understanding of the basics is. Look at some of the code that was open sourced by Yahoo years ago. Other large engineering organizations today have technology which far exceeds the complexity of what was made public by Yahoo a decade ago. Unfortunately Yahoo is pretty much the only example of a large company open sourcing big portions of their platform code.