Thinking outside the box.
In 2004 when the new monochrome ipod came out, known as the fourth generation ipod, it was impossible to run custom software on it, such as the Linux OS.
This was because it had an encrypted second stage bootloader. The previous generation ipods didn't.
A member of the ipodlinux community found a way to execute some limited amount of code, not enough to dump the decrypted bootloader. However the code could send instructions to the built in ipod piezo speaker. It could only make squeaks and clicks.
He proceeded to dump the bootloader by instructing the piezo speaker to squeak out the whole bootloader, which he recorded with a microphone - leading to the full jailbreak of the 4th gen ipod.
https://blog.codinghorror.com/ipod-hacking-via-modem/