How do I Display Two Continous Data Stream into OpenCV.imshow()?

Question

I have this project that combines two data from two different sensors, a TFLuna LiDAR and a Raspberry Pi Camera Module V2, for an Object Detection self driving vehicle. I've tried Threading both sensors to allow concurrent operation but I have trouble displaying those data together. Sometimes they work but the LiDAR data won't continously update itself. here's the code I'm using for the LiDAR:

def read_tfluna_data():
    while True:
        counter = ser.in_waiting # count the number of bytes of the serial port
        if counter > 8:
            bytes_serial = ser.read(9) # read 9 bytes
            ser.reset_input_buffer() # reset buffer

            if bytes_serial[0] == 0x59 and bytes_serial[1] == 0x59: # check first two bytes
                distance = bytes_serial[2] + bytes_serial[3]*256 # distance in next two bytes
                return distance

class lidar:

def update(self):
    # Keep looping indefinitely until the thread is stopped
    while True:
        distance = read_tfluna_data()
        return distance
        
def __init__(self):
    distance = Thread(target=self.update,args=())
    distance.start()

and this is the code for the display:

while True:
# Grab frame from video stream
frame1 = videostream.read()

# Acquire frame and resize to expected shape [1xHxWx3]
frame = frame1.copy()
frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
frame_resized = cv2.resize(frame_rgb, (width, height))
input_data = np.expand_dims(frame_resized, axis=0)

# Normalize pixel values if using a floating model (i.e. if model is non-quantized)
if floating_model:
    input_data = (np.float32(input_data) - input_mean) / input_std

# Perform the actual detection by running the model with the image as input
interpreter.set_tensor(input_details[0]['index'],input_data)
interpreter.invoke()

# Retrieve detection results
boxes = interpreter.get_tensor(output_details[boxes_idx]['index'])[0] # Bounding box coordinates of detected objects
classes = interpreter.get_tensor(output_details[classes_idx]['index'])[0] # Class index of detected objects
scores = interpreter.get_tensor(output_details[scores_idx]['index'])[0] # Confidence of detected objects

# Loop over all detections and draw detection box if confidence is above minimum threshold
for i in range(len(scores)):
    if ((scores[i] > min_conf_threshold) and (scores[i] <= 1.0)):

        # Get bounding box coordinates and draw box
        # Interpreter can return coordinates that are outside of image dimensions, need to force them to be within image using max() and min()
        ymin = int(max(1,(boxes[i][0] * imH)))
        xmin = int(max(1,(boxes[i][1] * imW)))
        ymax = int(min(imH,(boxes[i][2] * imH)))
        xmax = int(min(imW,(boxes[i][3] * imW)))
        
        cv2.rectangle(frame, (xmin,ymin), (xmax,ymax), (10, 255, 0), 2)

        # Draw label
        object_name = labels[int(classes[i])] # Look up object name from "labels" array using class index
        label = '%s: %d%%' % (object_name, int(scores[i]*100)) # Example: 'person: 72%'
        labelSize, baseLine = cv2.getTextSize(label, cv2.FONT_HERSHEY_SIMPLEX, 0.7, 2) # Get font size
        label_ymin = max(ymin, labelSize[1] + 10) # Make sure not to draw label too close to top of window
        cv2.rectangle(frame, (xmin, label_ymin-labelSize[1]-10), (xmin+labelSize[0], label_ymin+baseLine-10), (255, 255, 255), cv2.FILLED) # Draw white box to put label text in
        cv2.putText(frame, label, (xmin, label_ymin-7), cv2.FONT_HERSHEY_SIMPLEX, 0.7, (0, 0, 0), 2) # Draw label text

#Draw LiDAR Distance in corner of frame
cv2.putText(frame,'Distance: %s cm' %dist_data,(900, 700),cv2.FONT_HERSHEY_SIMPLEX,1,(255,0,0),2,cv2.LINE_AA)
#Draw Rudder in corner of frame
cv2.putText(frame,'Rudder dir: forward!',(50, 700),cv2.FONT_HERSHEY_SIMPLEX,1,(255,0,0),2,cv2.LINE_AA)
# All the results have been drawn on the frame, so it's time to display it.
cv2.imshow('Object detector', frame)
# Press 'q' to quit
if cv2.waitKey(1) == ord('q'):
    break

I've tried putting the .update() in the while True loop but it stalls the program and ended up crashing it. I've tried turning the serial port on'off, edited the boot.config to allow uart and turned off the USB serial.