In 2021, Google paid $26.3 billion to companies like Samsung, Apple, LG and Motorola to be the default search engine on those devices.
Obviously on Google's own devices, Google is the default search engine.
But Google's device section doesn't record that as revenue. The last thing Google needs is an accusation that it is spinning the books, even if it it wouldn't be shenanigans if Google's device section was a separate company.
Another way to look at it is for every additional Google Pixel customer, there is one fewer potential customer of the other makers. One less phone means smaller payments from search, which saves Google money by avoiding that expense.
Hypothetically, if Google search was paying Google devices to be Google's default search, would Google devices be profitable? Yes.