They wouldn't do it like that. They'd pull an App store or an Apple News. Block the world, whitelist publishers that jump through your hoops. Then it would be really easy to make a search engine if you are only crawling the top 100 sites or whatever that 99.999% of apple users are visiting anyhow. Most users would probably blind to the fact that this isn't close to actual search, and many more still wouldn't care. Some might actually like Apple removing the SEO spam that plagues google.

Or they could “pull an Apple podcast” - anyone can register their podcast for free, the actual MP3 are played from your server (unlike Google and Spotify) and there has been a documented API of its index that anyone freely use and that is used by many third party players on both iOS and Android. The API has been available since 2005.