Did you consider adding a password-changing webapp that connects via a smartphone's headphone jack? Or maybe even just with a _cheap_ piezo for bidirectional be

Did you consider adding a password-changing webapp that connects via a smartphone's headphone jack? Or maybe even just with a _cheap_ piezo for bidirectional beeping to a smartphone? Consider the equalizer commonly used in the output path of a smartphone, but there should be existing work you might be able to build on.