Have you ever heard of Minilyrics? Little program that downloads .lrc files (aka timestamped text files) and displays them in sync with the song like it's karaoke, compatible with most music players (...or at least it was a decade and a half ago). Plenty mp3 and mp4 players were compatible with the .lrc files themselves if you loaded them in alongside the music files, made long bus rides a bit less boring, actually being able to read the lyrics (...assuming no particular line was too long for that teensy little LCD screen, some .lrc files required a bit of fine tuning in that regard, heh). Any way point is, what you're talking about is tech that actually exists, and has existed for a long time. It wouldn't be that hard to re-dress it as an in-game thing, beyond game-specific logic (such as getting expies to stop singing if they drop the mp3 player or are being mauled to death). I've also found https://lrclib.net/docs as an alternative to Minilyric's own database. Bit more modern it seems, might be easier to work with.