Apple does not have a publicly facing search engine. They do have web crawlers which are potentially used for a variety of reasons. Rumor sites have seen this and projected that Apple will create a search engine.
One of these potential use cases is likely the results you see in Safari/Spotlight. It does not mean that Apple will ever make that publicly searchable.
The crawler definitely exists, and Apple says Products like Siri and Spotlight Suggestions use Applebot
I’m curious if any of these search results are available on the Mac outside Siri, and what indications you might use that this result is supplied by Applebot results vs Wolfram Alpha, or Wikipedia, or anything else that all gets glommed together into spotlight suggestions on iOS and so you can’t really know with results come from which source.