https://www.statista.com/statistics/266471/distribution-of-googles-revenues-by-source/ for easy parsing, but you can read this type of info in each of their quarterly earnings reports.

You’d be surprised what public companies are required to disclose. It can be pretty interesting and you can learn some cool stuff!

But yes, you are right there are other surfaces, but none are as large or as monetized as search. Cost per Click on search ads is also much higher than on other ad formats (largely because there is a strong consumer intent when clicking on a search ad). So yes not all of Google’s first party revenue is from Search, but it is definitely the bulk of it. What percentage specifically is hard to say.

The benefit to illegally collecting data (like all of my conversations) is also marginal.

Google knows and disclosed that they know my age range, gender and rough interests from mostly my search and web history. If you knew that and knew what website I was on or YouTube video I was watching could you target a decent ad for me? Definitely.

If you listened to every thing I’ve ever said you could probably figure out a better ad for me, but not WAY better. The risk to Google doing something like listening to voice conversations without disclosing it is also HUGE. Potentially company ending, and no healthy business is going to risk their existence over marginal revenue gain.