The one in OP’s picture is one such device. You plug it directly into the wall and it heats up. No fan though, just passive convection

Plex does alright at suggesting music from your own library, and also has some really nice DJ-like song transitions that are legitimately way better than any other track fades. However, Plex users have been frustrated with the company’s slow response to fixing long-standing bugs, and some of the features are paid. It’s also not open-source.

No idea if it can suggest music that isn’t in your library; I know that they integrate with Tidal though, so maybe if you have that it’ll also suggest stuff from Tidal?