Respect, "all-in" mindset, realizing that blowing the lid gains you nothing but 5 minutes of fame, and then losing your lucrative job at the most valuable company in the world.

By separating Research & Development of the fundamentals from the Development of the product (on top of having NDA's of course).

People and Media are not so much interested in technology research, and without a product it's also often too abstract to understand. If a company makes no publications or speeches at conferences, they can often work for YEARS without any special measureas and not getting noticed...

The product itself they then likely developed with the same business-practices to secrecy as an iPhone.

It wasn't that well hushed, there were persistent rumours for years. After all it was the running joke that apple were going to launch a VR headset each WWDC.

> How is one company able to hush all its employees

Not all employees are working on top secret projects, those who do very few get the overall picture, they just work on some individual features.