I keep recommending the teensy for this. It is an arduino clone that can act as HID or midi interface. Its not difficult to program it to once and for all to have input/output pins on midi notes.
If you are going to do it once, then I strongly reccomend the teensy. Or if you want to go wireless and want to put a bit more programming effort into it, then look at the ESP32 where you can use bluetooth low energy or a webserver to trigger.
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