Well, apparently you can extend Emacs to have it:
Emaccordion
Control your Emacs with an accordion — or any MIDI instrument!
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You can e.g. plug in a MIDI pedalboard (like one in a church organ) for modifier keys (ctrl, alt, shift); or you can define chords to trigger complex commands or macros.
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The idea for the whole thing came from [dead link]. I immediately became totally convinced that a full-size chromatic button accordion with its 120 bass keys and around 64 treble keys would be the epitome of an input device for Emacs.