I've wanted to build something like this for a long time, cool (and unsurprising, really) to see it's already done!
Swans is my number 30 by scrobbles but 4 by playtime, which makes total sense.
E.g. Fishmans - Long Season is a 40 minute song, but the website's considers it as divided into 4-5 parts. And you don't have to listen to the full song to get a scrobble.
In the Spotify data you get the exact number of seconds you listened to it. And it is surprisingly complete and easy to use too. With LLMs I bet you can load it into pandas and construct queries for any insight you want in seconds.
The advertising profile was especially interesting since a) I don't think the brands expected anyone outside of their marketing teams to see some of these names b) I've had premium for most of the time I've used Spotify, but they're still putting in full effort on generating an ad profile in case that ever changes