This an example of Spotify web player and YouTube installed as a PWA in Edge Version 91.0.862.0 (Official build) canary (64-bit)
in this version, which is the first time this is appearing in a installed PWA, only the downloads button/hub appears there. I hope in the future the Global Media Controls button also become available there, that will make the most sense.
we'll have to wait and see whether favorites, history or collections icons will be there too or not.