Bit of an intro : I just bought Glider last night mostly because I needed a way to chromecast my purchased music on my iPhone, and it works great. Looks great too - love the focus on album covers when playing.
I also love that you kept the way Apple Music does “Play Later” - thank you, no other music app seems to get this right (Spotify, Tidal, etc).
So to get to the point, I think one popular feature that would be useful would be a crossfade, something the Music App lost a long while ago.
Anyway nothing urgent or anything, just a thought, love the app as it is right now