com.spotify.Client VS psst

There is nothing "unsafe" about flatpak. In fact for every package on flathub you can see exactly what the "unofficial" packagers do in the corresponding github repository. For example here is the repository for Spotify, if you look at the json manifest file you can see they are repackaging the "official" Snap with the necessary libraries and scripts to support it running as a flatpak. Everything there is open source and able to be examined.

If you click on the "Manifest" link for the package on flathub, it will take you to where the code that packages the app resides. There you can review exactly what the packager does in the json manifest. Here's the one for the Spotify client, for example, which shows where it pulls in dependencies and where it downloads the proprietary code from (in this case they base it on the snap) and what commands it executes while packaging the flatpak.

Try installing it via Flatpak

Flatpaks builds are made to be reproducible. Everything is done openly and you can check how the apps like for example Spotify where made.

Why not just use the flatpak?

Judging by the manifest, the Spotify Flatpak is built from the Spotify Snap.

On the other hand, this Rust-based one called Psst looks awesome and works: https://github.com/jpochyla/psst

Psst but currently very limited in features and have to build yourself.

psst, https://github.com/jpochyla/psst

I don't know how can I install this open source software from github.

Would like to add that you can also use clients such as spotify-qt and Spotify TUI to control said "device". There's also Spot and psst that are standalone (librespot not required but no Connect functionality).

You can also take a look at Psst. I use Symphonia for decoding and CPAL or CubeB for output. CubeB is a bit nicer.

There's also this project, written in Rust, which is a great GUI Spotify client https://github.com/jpochyla/psst

There‘s a Spotify client, psst, which has an Async widget (with a Promise state struct) that works very well for loading states etc. That project has a bunch of other tidbits and interesting patterns for Druid, I learned a ton from the code.