@mattl I think some have been mentioned but as someone who's deep dived into automating artist/band/album/release/artwork retrieval the easiest to find matches would be the iTunes Search API (same goes for album art), MusicBrainz API (https://musicbrainz.org/doc/MusicBrainz_API) , Spotify API (https://developer.spotify.com/), and then last.fm/discogs. For live show data/setlists the best resource is setlist.fm and they have a friendly api (https://api.setlist.fm/docs/1.0/index.html ), for lyrics https://lrclib.net/ is the best (free, with db dumps and api!) otherwise you'll have to use a workaround hack for the genius.com api (which is against TOS) as they don't include full lyrics unless you pay an insane amount of $. Mixmatch is who caught google scraping their lyrics db and now they only offer paid subscriptions for their lyrics api. Cover art can be grabbed from the top sources i first mentioned (itunes, spotify, musicbrainz + cover art archive, last.fm). Audio ID (i.e. shazam) can be done using a number of methods. Here are some links to fill in the gaps & provide more resources for ya to pick through:
https://gist.github.com/0xdevalias/eba698730024674ecae7f43f4c650096#my-other-related-deepdive-gists-and-projects
and
https://metabrainz.org/projects

Big fan of the project btw!