Magento 2 code to dump only specific system settings when executing app:config:dump

magento2-config-dump-only-specific.php

// module.xml
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
    <module name="VendorName_ModuleName" setup_version="0.0.1" >
        <sequence>
            <module name="Magento_Config"/>
        </sequence>
    </module>
</config>

// di.xml
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <virtualType name="specificConfigInitialDataProvider" type="VendorName\ModuleName\Model\Config\Source\InitialConfigSource">
        <arguments>
            <argument name="reader" xsi:type="object">Magento\Framework\App\DeploymentConfig\Reader</argument>
            <argument name="configType" xsi:type="const">Magento\Config\App\Config\Type\System::CONFIG_TYPE</argument>
        </arguments>
    </virtualType>
    <virtualType name="appDumpConfigSystemSource" type="Magento\Config\App\Config\Source\DumpConfigSourceAggregated">
        <arguments>
            <argument name="sources" xsi:type="array">
                <item name="modular" xsi:type="array">
                    <item name="source" xsi:type="object">Magento\Config\App\Config\Source\ModularConfigSource</item>
                    <item name="sortOrder" xsi:type="string">10</item>
                </item>
                <item name="dynamic" xsi:type="array">
                    <item name="source" xsi:type="object">Magento\Config\App\Config\Source\RuntimeConfigSource</item>
                    <item name="sortOrder" xsi:type="string">100</item>
                </item>
                <item name="initial" xsi:type="array">
                    <item name="source" xsi:type="object">specificConfigInitialDataProvider</item>
                    <item name="sortOrder" xsi:type="string">1000</item>
                </item>
            </argument>
        </arguments>
    </virtualType>
    <virtualType name="specificConfigSystemSource" type="appDumpConfigSystemSource">
        <arguments>
            <argument name="rules" xsi:type="array">
                <item name="default" xsi:type="const">Magento\Config\App\Config\Source\DumpConfigSourceAggregated::RULE_TYPE_EXCLUDE</item>
                <item name="includeInConfigPhp" xsi:type="const">Magento\Config\App\Config\Source\DumpConfigSourceAggregated::RULE_TYPE_INCLUDE</item>
            </argument>
        </arguments>
    </virtualType>
    <virtualType name="skipDumpEnvSystemSource" type="Magento\Config\App\Config\Source\DumpConfigSourceAggregated">
        <arguments>
            <argument name="sources" xsi:type="array">
            </argument>
            <argument name="rules" xsi:type="array">
            </argument>
        </arguments>
    </virtualType>
    <type name="Magento\Deploy\Console\Command\App\ApplicationDumpCommand">
        <arguments>
            <argument name="sources" xsi:type="array">
                <item name="system" xsi:type="array">
                    <item name="source" xsi:type="object">specificConfigSystemSource</item>
                    <item name="pool" xsi:type="const">Magento\Framework\Config\File\ConfigFilePool::APP_CONFIG</item>
                    <item name="comment" xsi:type="string"></item>
                </item>
                <item name="system_env" xsi:type="array">
                    <item name="source" xsi:type="object">skipDumpEnvSystemSource</item>
                    <item name="namespace" xsi:type="string">skipSystem</item>
                </item>
            </argument>
        </arguments>
    </type>
    <preference for="Magento\Config\Model\Config\TypePool" type="VendorName\ModuleName\Model\Config\Type\TypeConfigPool" />
    <type name="VendorName\ModuleName\Model\Config\Type\TypeConfigPool">
        <arguments>
            <argument name="includeInConfigPhp" xsi:type="array">
                <item name="dev/js/merge_files" xsi:type="string">1</item>
                <item name="dev/css/merge_css_files" xsi:type="string">1</item>
                <item name="dev/static/sign" xsi:type="string">1</item>
            </argument>
        </arguments>
    </type>
</config>

// VendorName\ModuleName\Model\Config\Source\InitialConfigSource
<?php
/**
 * InitialConfigSource
 */
namespace VendorName\ModuleName\Model\Config\Source;

use Magento\Framework\App\Config\ConfigSourceInterface;
use Magento\Framework\Config\File\ConfigFilePool;
use Magento\Framework\App\DeploymentConfig\Reader;
use Magento\Framework\DataObject;

class InitialConfigSource implements ConfigSourceInterface
{
    /**
     * @var Reader
     */
    private $reader;

    /**
     * @var string
     */
    private $configType;

    /**
     * @var string
     * @deprecated 100.2.0 Initial configs can not be separated since 2.2.0 version
     */
    private $fileKey;

    /**
     * DataProvider constructor.
     *
     * @param Reader $reader
     * @param string $configType
     * @param string $fileKey
     */
    public function __construct(Reader $reader, $configType, $fileKey = null)
    {
        $this->reader = $reader;
        $this->configType = $configType;
        $this->fileKey = $fileKey;
    }

    /**
     * @inheritdoc
     */
    public function get($path = '')
    {
        $data = new DataObject($this->reader->load(ConfigFilePool::APP_CONFIG));
        if ($path !== '' && $path !== null) {
            $path = '/' . $path;
        }
        return $data->getData($this->configType . $path) ?: [];
    }
}
?>

// VendorName\ModuleName\Model\Config\Type\TypeConfigPool
<?php
/**
 * TypeConfigPool
 */
namespace VendorName\ModuleName\Model\Config\Type;

class TypeConfigPool
{
    const TYPE_INCLUDE_IN_CONFIG_PHP = 'includeInConfigPhp';

    private $includeInConfigPhp = [];

    public function __construct(array $includeInConfigPhp = [])
    {
        $this->includeInConfigPhp = $includeInConfigPhp;
    }

    public function isPresent($path, $type): bool
    {
        if (!isset($this->filteredPaths[$type])) {
            $this->filteredPaths[$type] = $this->getPathsByType($type);
        }
        return in_array($path, $this->filteredPaths[$type]);
    }

    private function getPathsByType($type): array
    {
        if ($type != self::TYPE_INCLUDE_IN_CONFIG_PHP) {
            return [];
        }
        return array_keys(array_filter(
            $this->includeInConfigPhp,
            function ($value) {
                return filter_var($value, FILTER_VALIDATE_BOOLEAN);
            }
        ));
    }
}
?>