little CircuitPython USB MIDI wrapper for the Adafruit Neo Trinkey SAMD21 USB. It forwards the touch inputs to control channels 1 and 2 and allows setting the LED's according to line

code.py

# for Adafruit Neo Trinkey SAMD21 USB https://www.adafruit.com/product/4870
# code is at: https://gist.github.com/GottZ/5e6477eccf36e6eda4f3ffa6b89d4e95
# revision 4
#
# touch pads will send control change events for 1 and 2 with 127 and 0 for their state
# when touching both at once, it will emit a control change event with id 3 additionally to 1 and 2
# if you want this with a delay, just remove # for all code lines that have been commented out
#
# the four neopixel LED's will respond to defined control change events as defined in the midipixels tuple
# 10, 20, 30 and 40 describe the led position. 10 is red, 11 is green, 12 is blue, 13 set's rgb to greyscale
# 50 is special, it will behave like a led but instead change all led's at once.

#import time
import board
import neopixel
import touchio
import usb_midi
import adafruit_midi

from adafruit_midi.midi_message import MIDIMessage
from adafruit_midi.control_change import ControlChange

# neopixels:
pixels = neopixel.NeoPixel(board.NEOPIXEL, 4, brightness=1, auto_write=False)

# touch pads:
touch1 = touchio.TouchIn(board.TOUCH1)
touch2 = touchio.TouchIn(board.TOUCH2)

# generic midi boilerplate:
midi = adafruit_midi.MIDI(
    midi_in=usb_midi.ports[0],
    midi_out=usb_midi.ports[1],
    in_channel=0,
    out_channel=0,
)

# state machines:
touch1_pressed = False
touch2_pressed = False
touch3_pressed = False # both touch inputs together
# you may enable these commented out things (also down in the code) to have a delay for the third touch event.
#touch1_ev = None
#touch2_ev = None
#touch3_delay = 0.1

# neopixel midi channels:
midipixels = {
    # bottom right
    10: (0, 0),  # red
    11: (0, 1),  # green
    12: (0, 2),  # blue
    13: (0, (0, 1, 2)),  # white
    # bottom left
    20: (1, 0),
    21: (1, 1),
    22: (1, 2),
    23: (1, (0, 1, 2)),
    # top left
    30: (2, 0),
    31: (2, 1),
    32: (2, 2),
    33: (2, (0, 1, 2)),
    # top right
    40: (3, 0),
    41: (3, 1),
    42: (3, 2),
    43: (3, (0, 1, 2)),
    # all 4 led's:
    50: ((0, 1, 2, 3), 0),
    51: ((0, 1, 2, 3), 1),
    52: ((0, 1, 2, 3), 2),
    53: ((0, 1, 2, 3), (0, 1, 2)),
}

while True:
    #now = time.monotonic()
    if touch1_pressed is not touch1.value:
        touch1_pressed = not touch1_pressed
        #touch1_ev = (None, now)[touch1_pressed]
        midi.send(ControlChange(1, (0, 127)[touch1_pressed]))

    if touch2_pressed is not touch2.value:
        touch2_pressed = not touch2_pressed
        #touch2_ev = (None, now)[touch2_pressed]
        midi.send(ControlChange(2, (0, 127)[touch2_pressed]))

    #if not touch3_pressed and touch1_pressed and touch2_pressed and (touch1_ev + touch3_delay) < now and (touch2_ev + touch3_delay) < now:
    if not touch3_pressed and touch1_pressed and touch2_pressed:
        touch3_pressed = True
        midi.send(ControlChange(3, 127))
    elif touch3_pressed and (not touch1_pressed or not touch2_pressed):
        touch3_pressed = False
        midi.send(ControlChange(3, 0))

    msg = midi.receive()

    if msg is None:
        continue

    if not isinstance(msg, ControlChange):
        continue

    control = msg.control
    value = msg.value

    if control not in midipixels:
        continue

    (pt, it) = midipixels[control]
    if type(pt) is not tuple:
        pt = (pt,)
    if type(it) is not tuple:
        it = (it,)

    for p in pt:
        for i in it:
            pixels[p] = pixels[p][0:i] + (value,) + pixels[p][i + 1 : 3]

    pixels.show()

20230426_130959.mp4

video showing how it can be used