Chrome is core to Google's business so it's worth it advertising, they also advertise the Pixel phone a lot in high-end places in global cities because they need to gain market share for mobile browsing and phones against Apple.
Anything else, not that important, even GCP which is their major bet doesn't really get any ads because it's a business product so not much sense in doing so.
They seem to believe word of mouth/viral marketing works because it worked for gmail and chrome, so they didn't double down on Stadia before product market fit, and that caused Stadia to fail(along with Google's short attention span reputation).
Anything else, not that important, even GCP which is their major bet doesn't really get any ads because it's a business product so not much sense in doing so.
They seem to believe word of mouth/viral marketing works because it worked for gmail and chrome, so they didn't double down on Stadia before product market fit, and that caused Stadia to fail(along with Google's short attention span reputation).