Can someone shed some light on why Apple would release this with only Apple Music as a music source?
Presumably there would have to be some kind of Spotify "app" running on the HomePod, to access Spotify without a phone, but there is no SDK for that yet
"HE-AAC (V1), AAC (16 to 320 Kbps), protected AAC (from iTunes Store), MP3 (16 to 320 Kbps), MP3 VBR, Apple Lossless, AIFF, WAV, and FLAC"
Not having to go to your computer and enabling AirPlay and selecting an album is kind of the point of a home assistant ;).