First of all, the purpose of this is to revive an old discussion, mainly targeting Android Marshmallow users, even perhaps any supporters.
I would like to say that Spotify, you have no clue by making this idea come true, would benefit lots non-modern phone users, allowing us to listen to music while saving lots of battery at the same time! In the Marshmallow ultra power saving mode, Marshmallow users can be able to use apps such as Facebook, WhatsApp, Email, with ultra power saving mode. I strongly feel like that individuals like me, who cannot afford to get a new phone, would really like that Spotify is showing care towards users without modern OS systems, by adding support for Spotify to be able to be used while Marshmallow's ultra power saving mode is on at the same time.
Cheers! Please add a Kudo or a Like (if that's what is used today) if you agree!
PS: If I posted this under the wrong category, mods please move this to the appropriate category. I apologize as I am not used to posting on this website.