How to programmatically create MIGX values in a snippet

foreach ($apiResults->data as $api_value){
  $document = $modx->getObject('modResource', array('longtitle' => $api_value->animalID));
  if(!empty($document)){ // update existing document
  	$document = $modx->getObject('modResource',array('longtitle' => $api_value->animalID));
  	$document->set('pagetitle', $api_value->animalName);
  	$document->set('content', $api_value->animalDescription);
  	if ($document->save() === false){ // Save the document
  		$modx->log(modX::LOG_LEVEL_ERROR,'An error occurred while saving your Resource!');
  		return false;
  	}

    $page = $modx->getObject('modResource',array('longtitle' => $api_value->animalID));

//this is where my issues are
    $i = 0;
    $pics = array();
    foreach($api_value->animalPictures as $animalPictures){
  	  if($i < 4){
        $pics[$i] = $animalPictures->urlSecureFullsize;
  		  if (!$page->setTVValue('pet_picture_'.$i, $pics[$i])) {
    			$modx->log(modX::LOG_LEVEL_ERROR,'There was a problem saving your TV animalPictures!');
    			return false;
    		}
  	  }
  		$i++;
    }
  	unset($pics); //cleanup
	} //endif
}//end foreach

$pics = array();
$i = 1;
foreach ($api_value->animalPictures as $animalPictures) {
    $pic = array();
    $pic['image'] = $animalPictures->urlSecureFullsize;
    $pic['MIGX_id'] = $i;
    $pics[] = $pic;
    $i++;
}

if (!$page->setTVValue('pet_pictures', $modx->toJson($pics))) {
    $modx->log(modX::LOG_LEVEL_ERROR, 'There was a problem saving your TV animalPictures!');
    return false;
}

$input = $doc->getTVValue('myMigx');
$res = $modx->fromJSON($input);
$count = count($res);

$new = array(
    'MIGX_id'       => $count + 1,
    'name'          => $scriptProperties['fields']['name'],
    'message'       => $scriptProperties['fields']['message'],
    'email'         => $scriptProperties['fields']['email'],
    'date'          => $scriptProperties['fields']['date'],
);
$res[] = $new;

if (!$doc->setTVValue('myMigx', $modx->toJson($res))) {
  $modx->log(modX::LOG_LEVEL_ERROR,'There was a problem saving your data!');
  return false;
}
 
return true;

<?php

$value = $doc->getTVValue('myMigx');
$items = $modx->fromJSON($value);

$next_id = 1;
//get the next MIGX_id
if (is_array($items)){
    foreach ($items as $item){
        $id = $modx->getOption('MIGX_id',$item,0)+1;
        if ($id > $next_id){
            $next_id = $id;
        }   
    }
}else{
    $items = array();
}
 
$item = array(
    'MIGX_id'       => $next_id,
    'name'          => $hook->getValue('name'),
    'message'       => $hook->getValue('message'),
    'email'         => $hook->getValue('email'),
    'date'          => $hook->getValue('date'),
);
$items[] = $item;
 
if (!$doc->setTVValue('myMigx', $modx->toJson($items))) {
  $modx->log(modX::LOG_LEVEL_ERROR,'There was a problem saving your data!');
  return false;
}
  
return true;