Google doesn't work like this.
People can almost autonomously spawn up small projects.
If it looks promising they keep getting more resources until it either has explosive growth and profits or someone higher in the chain thinks there isn't a current viable path for THAT version of the project to profitablity.
Google might believe in XR and keep funding these small projects, but if none of them display evidence that that particular approach is going to be huge, then they move on.
It's not top down.
Sundar doesn't say, we need more XR. Team, go find me the most promising options, and then we'll fund it to the moon. And then a month later he gets bored and says, no, never mind, kill that. Let's chase another hype bubble. Only to then months later come back and say, team, we need more XR!