It's equivilant to tree ring dateing used in archiological research, and I wonder, if like wood, there is other data embeded.

I love this product. Would it be possible to also accept a URL for analysis?

This is definitively possible. Are you thinking about YouTube or social media links?

Those come to mind, but also Internet Archive item links; this enables potentially dating any video or audio content in their archive (assuming it contains the necessary audio data from mains). I admit this is lazy, as it is easy to retrieve the content and then upload, but still worth mentioning in case it was value product feedback.