Spotify does work with Siri on iOS but does not work with Siri on Homepod/Homepod Mini. They complain in their Time to Play Fair website about Apple not giving

Spotify does work with Siri on iOS but does not work with Siri on Homepod/Homepod Mini. They complain in their Time to Play Fair website about Apple not giving them access to Homepod, but Apple provided them access over two years ago. Also since Homepod uses standard Siri support that Spotify already has in iOS, it's not like it would be significant engineering effort to get it to work, so this is purely Spotify trying to spite Apple. They don't even have AirPlay 2 support yet! Every other major music service supports AirPlay 2 and Homepod already for some time now.