I have three basic, PERSONAL configurations of autoharps so that I can play a variety of styles. Each has its advantages and limitations. I am the first to admit they require extreme conversions and, though they meet my needs, I am not trying to convince anyone else, just putting the info out there for those who might find it of interest.
The Chromatic Deleter, which creates simple chords out of scales or more complex chords by blocking out certain notes opened by single buttons
The Perfect Fifth diatonic, which adds microtonal second steps to the scale in order to better manage the compromises inherent in Western music and allow the fifth intervals of the I, IV, and V chords to be just.
The Modal Minor Pentatonic, which also has lock bars and delete buttons so that modal harmonies can be derived from a five note scale with a kind of drone. When lock bars are not engaged, it functions as a single key diatonic.
Again, not everyone's cup of tea. However, the song arrangements are created so that they can be played on more-or-less standard autoharps in conventional keys with progressions that are intended to be recognizable but not too boring.