<?xml version="1.0" encoding="utf-8"?>
<extension version="4.0" type="plugin" group="task" method="upgrade">
    <name>plg_task_testarticlepublish</name>
    <author>Author Name</author>
    <creationDate>2023-09-15</creationDate>
    <version>1.0.0</version>
    <description>Description of the plugin</description>
    <files>
        <filename plugin="testarticlepublish">testarticlepublish.php</filename>
    </files>
</extension>

<?php
defined('_JEXEC') or die;

use Joomla\CMS\Factory;
use Joomla\CMS\Plugin\CMSPlugin;

class PlgTaskTestarticlepublish extends CMSPlugin
{
    public function onTaskExecute($taskContext, $params)
    {
        // Ensure this task is for us
        if ($taskContext !== 'plg_task_testarticlepublish')
        {
            return;
        }

        $db = Factory::getDbo();
        $query = $db->getQuery(true)
            ->select('*')
            ->from($db->quoteName('#__content'))
            ->where($db->quoteName('state') . ' = 0') // Unpublished
            ->where($db->quoteName('title') . ' LIKE ' . $db->quote('%test%')) // Title contains "test"
            ->where($db->quoteName('publish_up') . ' > ' . $db->quote(Factory::getDate()->toSql())) // Publish date in the future
            ->order('created ASC')
            ->setLimit(1);

        $article = $db->setQuery($query)->loadObject();

        if ($article)
        {
            $article->state = 1; // Set to published
            $db->updateObject('#__content', $article, 'id');

            // Trigger the onContentAfterSave event
            Factory::getApplication()->triggerEvent('onContentAfterSave', ['com_content.article', &$article, false]);
        }
    }
}

<?php

// We are a valid entry point.
const _JEXEC = 1;

if (!defined('JPATH_CLI'))
{
    define('JPATH_CLI', __DIR__);
}

require dirname(__DIR__) . '/includes/defines.php';
require dirname(__DIR__) . '/includes/framework.php';

use Joomla\CMS\Factory;
use Joomla\CMS\Application\CliApplication;
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;

class PublishTestArticleCommand extends Command
{
    protected static $defaultName = 'article:publish-test';

    protected function configure()
    {
        $this->setDescription('Publish the oldest unpublished article with "test" in the title and future publish date.');
    }

    protected function execute(InputInterface $input, OutputInterface $output): int
    {
        $db = Factory::getDbo();
        $query = $db->getQuery(true)
            ->select('*')
            ->from($db->quoteName('#__content'))
            ->where($db->quoteName('state') . ' = 0') // Unpublished
            ->where($db->quoteName('title') . ' LIKE ' . $db->quote('%test%')) // Title contains "test"
            ->where($db->quoteName('publish_up') . ' > ' . $db->quote(Factory::getDate()->toSql())) // Publish date in the future
            ->order('created ASC')
            ->setLimit(1);

        $article = $db->setQuery($query)->loadObject();

        if ($article)
        {
            $article->state = 1; // Set to published
            $db->updateObject('#__content', $article, 'id');

            // Use the new event dispatching system
            $dispatcher = Factory::getContainer()->get('dispatcher');
            $event = new \Joomla\CMS\Event\ContentAfterSave('onContentAfterSave', ['context' => 'com_content.article', 'item' => $article, 'isNew' => false]);
            $dispatcher->dispatch('onContentAfterSave', $event);

            $output->writeln('<info>Article published successfully!</info>');
        }
        else
        {
            $output->writeln('<comment>No matching article found.</comment>');
        }

        return Command::SUCCESS;
    }
}

// Create the application.
$cli = CliApplication::getInstance('PublishTestArticleCommand');
$cli->addCommand(new PublishTestArticleCommand);
$cli->execute();

Interesting approach. I have not tried ChatGPT for anything serious yet. Interestingly, the two examples above are just variations of what I've been doing all along. The CLI example does add a command, but I don't think the ->execute method executes the command. I think it executes adding the command to the application. Both examples more or less confirm that my code is on the right track.