That sounds like https://news.ycombinator.com/item?id=33910863 which was posted here on HN a few weeks ago. It's a ChatGPT-esque model that provides URLs for where it synthesized each individual sentence from, but also feels a lot more summary-heavy rather than strictly new text a la ChatGPT. The results leave quite a bit to be desired, but it's nice to know there are people working on exactly what you're suggesting. :)

OpenAI, specifically, has also been working on allowing GPT models to browse the internet and include citations with e.g. https://openai.com/blog/webgpt/