let's see:
> spent most of his time working on "default search engine" (or "default web browser") deals before taking the CEO job
even if we take your convenient assumption as correct ("it's reasonable to say that those deals would have fallen under his ambit"), it's still wouldn't be a true statement. But feel free to point out which part is true if we relax any more assumptions.
Based on Pichai being the senior executive at Google responsible for Chrome browser and search defaults, as a matter of public record he held corporate responsibility for getting google search as the default search engine on as many devices as possible.
You stated that the original commenter was mistaken with no supporting evidence and a high level of acrimony in your phrasing. I'd be interested to see supporting evidence for why you think the commenter was mistaken, in the context of the other resources they provided.
While the comment might be a little oversimplified, I think it's reasonable to say that those deals would have fallen under his ambit. And there's no question that Chrome and Android are the two central planks of Google's search distribution monopoly with consumers, along with the Apple deal.
[1] https://www.businessinsider.com/how-sundar-pichai-rose-to-be...