I’ve noticed very recently (last several weeks) Siri (via my HomePod) is able to competently answer some very nuanced world knowledge questions that are sourced to random but still reputable websites — it appears to paraphrase enough to appear to be directly answering your question and then cites the source website. It only seems to get fouled up if it’s possible to confuse the question for something supposedly actionable that it chokes on. I have an Amazon Echo in the same room and usually direct such questions to Alexa, but trial Siri every so often to check for progress. And suddenly Siri just started giving appropriate answers with citations. It’s like they just hooked up something new to the Siri knowledge graph, and it’s pretty good.