It's the same with Apple Music and Apple devices, just not Alexa (yet). My issue with Spotify is the service is horrendous. Their song library and download limits are an absolute joke, their solution for uploading missing content (like albums from Tool) is half-baked, and their lack of smart playlist support (at least for liked/loved content) is laughable especially considering the PC software I used in 1998 to manage my Rio 600 portable mp3 player supported those. I would like to switch to Spotify due to working on absolutely everything and it's a good service for music discovery and for people who want to be spoon-fed their content but it's a non-solution for people with large libraries and for content not available on the service. Spotify has shown zero intentions of fixing any of this and are now focused on expanding their reach into podcasts instead of actually making their service better.
It's both. Apple Music support was contacted by someone on Reddit and, after going back and forth for a week, someone working on the project said that they (Apple) were working closely with Amazon to make it better but don't have a timeframe for when that will happen. I've been using Amazon Music, the "free" tier for Amazon Prime members, to hold me over until Apple Music really gets integrated.
Apple hasn't but Amazon has, in a roundabout way. Amazon released their Amazon Music API to developers in the U.S. only. That's the API that allows them to develop their service with Alexa compatiblity instead of having to only go through Amazon. Apple (and others) can't really do anything until Amazon opens the API to more territories.
Do you even pay for Spotify?