I know of promoted content on app stores but don't know if they did paid listing. I just know that since coinbase is an extremely popular app that is why it's not so surprising to see them achieve such a feat after their listing on both app stores. It's like the #1 crypto app for years now on app stores at the moment during to their premium-like service offerings especially to retail and mainstream investors and users. Even in terms of usage, it's a top app.