[Frank Cox]

A flat symbol isn't part of the default font set on Android devices so you're outta luck for a "real one".   A lower case b is about as good as it gets, really. You could just arbitrarily select another character and call that a flat symbol but that might be confusing.

Colours might be an option to consider.  Chords in red and notes in blue or something.  It's still not what you want though.