Try this tip to listen to Music on more than one device even when your Music Unlimited or Prime plan won't allow it.
6 Music Sync Apps to Stream Music to Multiple Devices - TechWiser
How to play music on all of your Alexa devices
How Do I Play Music on Multiple Devices
Airplay 2 Music Streamer Receiver, WiiM Mini
How to Have Alexa Play Music on All Devices - Smart Home Rig
Can I Stream Spotify Music on Multiple Devices? : r/TunePat_Music
How to Play Spotify on Multiple Devices Simultaneously [8 Ways]
How to Play Spotify on Two Devices Simultaneously [Updated]
Music IO Update Lets You Stream Audio + MIDI Between Multiple
Play Same Music on Multiple Devices!
How to Sync Apple Music between Multiple Devices
How to Play Spotify Music on Multiple Devices?
IPTV Multiple Devices — How to Stream IPTV on Multiple Screens
How to listen to Spotify on multiple devices or speakers
6 Music Sync Apps to Stream Music to Multiple Devices - TechWiser