Clarification, Google doesn’t sell the info itself, it guards that jealously, they sell targeted advertising. They say “we can make sure your advert gets to the people who want your stuff” to the ad companies and sell advertising space on that premise. The ad companies don’t know your political leanings, but Google does and makes its money by targeting you with ads relevant to that and other aspects they’ve identified about you.
Google/Meta don’t sell the info specifically because that info is how they provide their “unique” service.