[yunohn]

These deals are based on market share, user activity and usage, and so on. No search engine is paying Vivaldi as much money as Yahoo or Google did to Firefox. It would be laughable to expect that kind of sponsor money for a niche browser that also reduces ad tracking. That’s how these things work.

[zamadatix]

It'd be laughable to expect Vivaldi needs the exact same 600 million dollar search deal that floats the entire Mozilla foundation to fund a custom Chromium UI.

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.