If you have Spotify Premium, it's been possible for years to set up a Spotify Connect receiver, and you can control your connect receivers via API, so it is in fact possible to use a third party client, if one exists.
Spot knocked it out of the park with this approach. If you just want the Spotify Receiver, you could use the underlying library that doubles as a CLI, librespot, but Spot serves as a nice example of using the Spotify APIs to actually search your library and control the receiver without the Spotify app and handles this all for you.
Connect isn’t bad if your primary method of listening to music is through smart speakers or a home entertainment setup with a receiver or something, but it’s unnecessarily complicated if you just want to listen through headphones on your PC and downright impractical for mobile listening.
As for librespot, it’s nice work but it’s also technically against the TOS since it’s reverse engineered, which means Spotify could ban users using it whenever they like. There’s also risk of your favorite app using it going away if they decide to take legal action against the project.
Spot knocked it out of the park with this approach. If you just want the Spotify Receiver, you could use the underlying library that doubles as a CLI, librespot, but Spot serves as a nice example of using the Spotify APIs to actually search your library and control the receiver without the Spotify app and handles this all for you.
https://github.com/xou816/spot