qmk_firmware/keyboards/40percentclub/gherkin/kb2040/keyboard.json

{
    "development_board": "kb2040",
    "matrix_pins": {
        "cols": ["GP8", "GP7", "GP6", "GP5", "GP4", "GP3"],
        "rows": ["GP26", "GP18", "GP20", "GP19", "GP10"]
    },
    "diode_direction": "COL2ROW",
    "backlight": {
        "pin": "GP9",
        "driver": "software"
    }
}