Sounds like you’re looking more on the download end of things. Nevertheless, if you have unidentified tracks, it may still be worth running them through Picard. It can search its DB using existing partial metadata, or do something like hash portions of the file and check its DB for matches. It really helped me cut down the unidentified and orphan mp3s in my collection.
You could potentially try the app Innertune for the first part of your query.