I think that highlights one of the reasons why, in this case, hardware has not been hard. (besides the fact that you are very clever)

The value you have created is actually more in the App than in the hardware.

As a maker of small devices (mostly open source) including MIDI - and putting aside commercial aspects like injection molding - I could recreate the hardware side of this project without much issue. The necessary components are likely already in this room with me. (I won't - I'm not in the business of copying things that people don't want copied)

But I'm not a software engineer, and therefore could not produce software of the scope and quality that you have, which is where the unique functionality of your device sits high above the relatively simple "receive MIDI data from MIDI devices" principle of the hardware by itself.