Unfortunately it looks like that one is for Apple devices, whereas I use Linux on desktop and Android on mobile.

There’s some, but I haven’t seen any that have the main features Plex and Plexamp have:

• Cross-fading when playing random tracks, but gapless playback when playing an album in order
• Analysis of the music using a local neutral network, such that you can tell it to play play “similar” sounding songs to the current one
• Automatic playlists - liked songs, decades, etc
• Downloads for offline playback
• Multiple libraries, for example I keep regular music separate from DJ mixes
• Equalizer with presets for common headphones

And probably other things I’m forgetting.