Firefox makes the vast majority of that income via their Google partnership. Vivaldi claims they do not get paid by Google.
The browser's market share will ultimately determine the market value of the search partnership, so Vivaldi will likely have a much lower income from it than Firefox, but it's in no way limited by whether they partner with Google or with any other search provider. For a smaller more efficient team, not maintaining their own browser engine, it could easily compare in sustainability to Firefox's income stream.
But my point was more around how the minimal amount of money coming from other search engines or sponsored bookmarks can’t sustain a browser dev team.
So there are definitely other decent sources of income besides Google for these deals and since it's a significantly more focused organization it doesn't seem implausible to me.
As I said, there are definitely other decent sources of income besides Google for these deals and since it's a significantly more focused organization it doesn't seem implausible to me.
But here's why there's confusion. Yahoo search at the time (or shortly before or after) switched to using Bing's search and ad engine.