I did briefly consider a password system, but they would have to be annoyingly long.
One thing you can do however is boot your Playdate into disk mode and navigate to Data -> com.tizianzeltner.musicbox -> tunes. There you can find super simple text files that you can share with others.
(You can also edit them on a computer that way. These are mostly a 48x18 grid of 0s and 1s to denote active or inactive pins on the barrel.
And probably best to make a backup of what is already there before changing anything.