How to render a subform custom field manually by using php in Joomla! 4.0.x

fancysubform.php

<?php
/**
 * @package         Joomla.Plugin
 * @subpackage      Fields.Subform
 *
 * @copyright   (C) 2019 Open Source Matters, Inc. <https://www.joomla.org>
 * @license         GNU General Public License version 2 or later; see LICENSE.txt
 * @contributor   Alexandre ELISÉ <contact@alexapi.cloud> Modified version on 2021-12-08
 * @description The content of this file needs to be copied in 
 * YOUR_JOOMLA_WEBSITE_ROOT/templates/cassiopeia/html/layouts/com_fields/field/fancysubform.php
 */

use Joomla\Component\Fields\Administrator\Helper\FieldsHelper;

defined('_JEXEC') or die;

if (!array_key_exists('field', $displayData))
{
	return;
}

$field = $displayData['field'];

$context = $field->context;

if (!$context || empty($field->subform_rows))
{
	return;
}

// remember you don't use prefix or suffix in your subform custom field so use it for something useful
$subformContainerClass = $field->params->get('prefix', '');

$subformResultClass = $field->params->get('suffix', '');

$result = '';

// Iterate over each row that we have
foreach ($field->subform_rows as $subform_row)
{
	// Placeholder array to generate this rows output
	$row_output = [];

	// Iterate over each sub field inside of that row
	foreach ($subform_row as $subfield)
	{
		$class   = trim($subfield->params->get('render_class', ''));
		$layout  = trim($subfield->params->get('layout', 'render'));
		$content = trim(
				FieldsHelper::render(
						$context,
						'field.' . $layout, // normally just 'field.render'
						['field' => $subfield]
				)
		);

		// Skip empty output
		if ($content === '')
		{
			continue;
		}

		// Generate the output for this sub field and row
		$row_output[] = '<div class="field-entry' . ($class ? (' ' . $class) : '') . '">' . $content . '</div>';
	}

	// Skip empty rows
	if (count($row_output) == 0)
	{
		continue;
	}

	$result .= sprintf('<div class="fields-result %s">%s</div>', ($subformResultClass ? (' ' . $subformResultClass) : ''), implode('', $row_output));
}
?>

<?php if (trim($result) != '') : ?>
	<div class="fields-container <?php echo($subformContainerClass ? (' ' . $subformContainerClass) : ''); ?>">
		<?php echo $result; ?>
	</div>
<?php endif; ?>

fancysubformarticlelayoutoverride.php

<?php
declare(strict_types=1);

/**
 * Subform Custom Field Manual Rendering
 *
 * @version       0.1.0
 * @package       fancysubformlayoutoverride.php
 * @author        Alexandre ELISÉ <contact@alexapi.cloud>
 * @copyright (c) 2009-2021 . Alexandre ELISÉ . Tous droits réservés.
 * @license       GPL-2.0-and-later GNU General Public License v2.0 or later
 * @link          https://alexapi.cloud
 * @description  this file should be placed in 
 * YOUR_JOOMLA_WEBSITE_ROOT/templates/cassiopeia/html/com_content/article/fancysubformarticlelayoutoverride.php
 * Then choose this layout for the article with the subform custom field 
 * 
 */

use Joomla\Component\Fields\Administrator\Helper\FieldsHelper;

defined('_JEXEC') || die;

// minimum code to render manually a custom field in an article
// based on it's name rather than on it's id

$customFields = $this->item->jcfields;

// custom fields by id ]
// not that useful in this case since jcfields is already indexed by id
//$customFieldsById = ArrayHelper::pivot($customFields, 'id');
//$subformCustomField = $customFieldsById[13];

// OR (uncomment the one you wanna use)

// custom fields by name
//$customFieldsByName = ArrayHelper::pivot($customFields, 'name');
//$subformCustomField = $customFieldsByName['article-bio'];

// the default layout of custom field
// you can specify here your own layout
// for example: field.fancysubform
// but you will first need to create that layout in
// YOUR_JOOMLA_WEBSITE_ROOT/templates/YOUR_TEMPLATE/html/layouts/com_fields/field/fancysubform.php
// if you want a basis copy paste the content of
// YOUR_JOOMLA_WEBSITE_ROOT/components/com_fields/layouts/field/render.php


$computedLayout = sprintf('field.%s', $customFields[13]->params->get('layout', 'render'));
echo FieldsHelper::render('com_content.article', $computedLayout, ['field' => $customFields[13]]);

user.css

/*
* Subform custom field styling
* This file needs to be in YOUR_JOOMLA_WEBSITE_ROOT/templates/cassiopeia/css/user.css
*/

.fancy-result.fancy-bio {
  display: grid;
  grid-template-columns: 1fr;
  grid-template-rows: auto;
  justify-items: center;
  border: 1px solid #ededed;
  max-width: 25vw;
  background-color: var(--fancy-secondary-color);
  backdrop-filter: brightness(2%);
  padding: 0.5rem;
  border-radius: 0.5rem;
}

.field-entry.fancy-render.fancy-firstname,
.field-entry.fancy-render.fancy-lastname,
.field-entry.fancy-render.fancy-phone
{
  display: grid;
  grid-template-columns: 6rem 1fr;
  grid-template-rows: auto;
  align-items: center;
  width: 100%;
}


.fancy-label {
  background-color: coral;
  color: black;
  margin: 2px;
  padding: 2px;
  border-radius: 2rem;
  max-width: 6rem;
  max-height: auto;
  text-align: center;
}

.fancy-value.fancy-photo img {
  border-radius: 50%;
  max-width: 100%;
  max-height: 100%;
}

span.field-value.fancy-value.fancy-firstname,
span.field-value.fancy-value.fancy-lastname,
span.field-value.fancy-value.fancy-phone {
  text-align: center;
  color: white;
}