sounds really exhausting... if that's the constant expectation and you're actually good at it, why work for Google at all and not fundraise for yourself? cuz you're doing all the same legwork but your ideas go to the man.
If you are happy being handed pre-scoped work, you can just stay at L4, which many people do.
It's not like that at all. Possibly it's like that for a high level PM, but for a SWE, it's more about putting yourself on the right project. You certainly don't have to constantly be coming up with new products on your own.