You don't need power to make music with an original Game Boy.
Music made with a Game Boy or another classic machine, commonly known as the chiptune, is nothing new. YouTube's MrSeberi, aka Sebastian Bender, may have wanted to join the chiptune scene, but probably couldn't find any batteries for his original Game Boy. Instead, he turned the device into a drum machine with no power at all.
Bender put together a song using various Game Boy-themed sounds. The simplest of the bunch include pressing the A and B buttons, pressing the D-pad, and flicking the front and back with his finger.
When he gets into it, the song uses flings of the Game Boy's battery springs, tosses of Game Boy cartridges, the removal of a Game Boy Camera, flipping the on/off switch, and scraping the Game Boy's ridged side. You wouldn't think all of those things mixed together would sound like anything coherent, but they do.
Okay, so the feedback from almost inserting a pair of headphones into the Game Boy's headphone jack might require some power, but it's still a pretty abstract technique in terms of musical composition. We can only hope Bender has a Virtual Boy song coming up next.