Interesting. Do you know if this extends to basically all digitized music regardless of the specifics of artist/label streaming preferences? Eg King Crimson’s catalog was never added to Spotify, if I link my ripped CDs to AM, would it make it available for me to stream on my phone?
I believe, yes. I have various live versions of albums that have been ripped from streams and radio, Apple tries to match them to their library to save space and then just lets you wifi sync them. Shows up right next to the other music in your library.
The feature is called iTunes Match- you can actually get it standalone from Apple Music (at least you could, not sure if they have changed anything recently,) but AM includes it:
