That's really the thing with Google. They have this huge empire and they build on top of their other work. This is why Apple Maps could never come close to competing with Google Maps. This is why Google Home at launch already did a far better job at understanding queries than Alexa which has been out for 2 years.
They're so well situated, with a years worth of technology and tools, so it's really hard for a new comer to compete.
Everything at Google is an internal Google secret made by Google for Google. ALL the software and ALL the hardware that's running it.
Services rely on lower-level services. If you want to copy the high level service yourself and executes it at the same level Google does, you'd need to have everything it depends on. Too bad for you, each piece is a multi billion dollar projects itself, with its own dependencies...
Let's imagine for a minute that there was a service that is somewhat standalone-ish. You may consider poaching the handful of people who can make it, for $1M a head. But that won't work well because money is not everything and you can't help it. Whenever there are ONLY 50 people in the world who can deliver what you need and you need almost all of them, you're fucked.
In short, the castle is out of reach, even the building bricks are out of reach ;)