SUMMARY Could you add the tagging libraries of Apple Music and Amazon Music as well? I know Amazon is listed. But some Amazon music tag are not showing up in the searches for me, so I'm wondering if it's just Amazon and not Amazon Music that's it's listing.
I have not seen that these sites offer more information relevant for tagging than Discogs or MusicBrainz. Is there an API to get information? I do not think that it is worth just parsing the (probably constantly changing) HTML output from these web sites.
Hmm, there's some sort of API for Apple Music at least: https://developer.apple.com/documentation/applemusicapi I have no knowledge of how to use it, so I don't know if it's actually usable for the situation of trying to pull data based on text matching - there's at least one example of a macOS script that is intended for augmenting an Apple Music library, but uses Discogs as its data source (https://github.com/certuna/Applescripts-for-Music), so Kid3 might already be using the most relevant/available source?