Staff engineers (in the FAANG parlance) are, generally speaking, ICs who were previously senior engineers who have proven themselves enough that they're trusted to be roughly autonomous, they're kind of "peers" to engineering managers in a way. While a senior engineer will typically not have the political capital move big politically-heavy rocks, it is typically down in the staff engineer's job description that they are expected to. It's basically shifting from a focus on code and building systems to people/the org and architecting systems that fit the org.

"Did the person get rewarded for this huge effort" Money-wise? Haha. No. Only in the sense that they further solidified their soft power as someone you shouldn't bet against. And of course the sense of pride that comes with shipping something (that further enriches some capitalist and maybe yourself to 0.0013% of the effect, since that's how much of the company your grant commands shares of).