I found out that the Ender Dragon has music while you fight her, which ends after she dies.
Use this pack to have Minecraft: Dungeons's Nameless One's boss fight music while fighting the Ender Dragon!
Discord: discord.gg/KYzdd3E
Credit for music track: https://www.youtube.com/watch?v=b5B4xK9RG4k
All rights go to Mojang (Peter Hont)