First of all, let's look at the "truly great" things Google has done -- search, ads, Android, YouTube, Maps, Gmail, Apps/GSuite/Workspace, and so on. 100% commitment, 100% great.
You say Google is "rather uncommitted" to GCP, which is hilarious if you'd look at the billions they've sunk into it. They committed to competing with AWS and by god they're spending the money to do it, and they're almost at profitability after more than 10 years of staying the course. If that's not commitment, then I literally don't know what is.
The rest of what you're listing is just that it's very hard to achieve profitable product-market fit, even if you're Google. Hardware like Pixel is hard to turn into a series of reliable successes, consumers just didn't sign up for Stadia in the numbers needed, Hangouts is a complicated story but Google certainly keeps trying with messaging, and FB Messenger's popularity was not even remotely a result of Hangouts splitting.
And just checking -- you think the 4th largest company in the world has the worst business people in the world...? No amount of genius engineering is going to get you there without an awful lot of genius business and product people too...