Apple announced SiriKit Media Intents at WWDC 2020 to let third-party music services to be integrated on the HomePod. As of today I think you can connect a user account from Deezer, Pandora, iHeartRadio and TuneIn Radio (according
to this)
Spotify has not released support in 2,5 years. Apple should really update the support page and not use Spotify as an example (they also mention Pandora on the page). A guess is that the person who wrote the support page thought it was just a matter of months before Spotify would implement HomePod-integration, since they historically had been very vocal about Apple not allowing third-party support, e.g. regarding Apple Watch.
But sadly, Spotify has not delivered. Worse is they don´t give any updates about their plans. There is a request on their forums, go there and vote if you care. Spotify probably won´t care...
Details Just this week at WWDC (June 22, 2020), Apple announced support for third party music services on the HomePod. I'm requesting that Spotify implement native support for the HomePod such that one or even multiple HomePods will appear in the "Connect to a device" menu on any Apple device...
community.spotify.com
I´m still a Spotify user scince I haven´t bothered switching playlists and so on, and AirPlay to the homepods works. But I´m a deeply dissapointed Spotify user.
