This used to be true but isn’t anymore. For a while they pushed Angular, nowadays I think a lot of teams are using react. GWT is long deprecated and gone.
From what I understand (no special insider information) React is essentially non-existent inside of Google, and NPM is not even available to engineers (be default)
It depends what org you're in. Cloud seems to use a lot of Angular, but the rest of the company is coalescing around an in-house framework called Wiz (you can poke around the open sourced jsaction library to get an idea of the design philosophy).
To be fair, gmail was quite great at the time of GWT. Not sure how much use their Clojure “platform” still get, but I think it was very ahead in terms of maintainability of large js code bases (or even ahead as we have it now)
