I am trying right now with Max2Play.
It has Spotify connect plugin, based on librespot and i think it doesn’t need LMS.
But because I don’t have Premium account, I suppose I can’t control the player.
I suppose even piCorePlayer has spotify connect plugin, I have to try.
Spotty is tricky to setup, and needs LMS.
Maybe you could also try Max2Play, but it has to be licensed.
Anyways, you can have 3 monts trial from this link..