thebluelad

Symfonium has been great in my experience and does offline and caching. Check it out: https://symfonium.app/

If you listen on high-end equipment the audio quality is noticeably worse than many other solutions and depending on your music taste, Spotify often removes content or doesn't have it in the first place.

I use Navidrome with Feishin as a client on PC and Symfonium on my phone. Symfonium allows me to cast in the same way as Spotify.

Symfonium is paid but appears to be one of the rare apps that is still thoughtfully created by somebody who actually uses it. The developer deserves the support.