NewsCacheAutoConfigurationService.php

<?php

namespace MyVendor\MyPackage\Service;

use TYPO3\CMS\Core\Core\Environment;
use TYPO3\CMS\Core\Database\ConnectionPool;
use TYPO3\CMS\Core\Utility\GeneralUtility;

/**
 * Use in ext_localconf.php with ExtensionManagementUtility::addTypoScript()
 *
 * Returns an @import TypoScript statement to a file that contains news TypoScript cache configuration.
 * The file is written on demand to a cache folder and automatically cleared with "Flush frontend caches".
 *
 * The included TypoScript configuration will make sure all pages which include news plugins, will respect
 * all news folders (starttimes, endtimes) when calculating their caching lifetime.
 */
class NewsCacheAutoConfigurationService
{
    public static function constructNewsCacheDefinition(): string
    {
        $filePath = Environment::getVarPath() . '/cache/data/assets/newsCacheConfiguration.typoscript';
        if (!file_exists($filePath)) {
            $content = self::getCacheDefinition();
            $fileHandle = fopen($filePath, 'w');
            fwrite($fileHandle, $content);
            fclose($fileHandle);
        }
        return '@import "' . $filePath . '"';
    }

    protected static function getCacheDefinition(): string
    {
        $newsStoragePIDs = [];
        foreach (self::getPageIdsOfNewsStorageFolders() as $storageFolderUid) {
            $newsStoragePIDs[] = 'tx_news_domain_model_news:' . $storageFolderUid;
        }
        if (empty($newsStoragePIDs)) {
            return '';
        }
        $newsStoragePIDlist = implode(',', $newsStoragePIDs);

        $cacheDefinition = [
            '# Auto generated by ' . self::class,
            'config.cache {',
        ];

        $pagesWithNewsPlugins = self::getIdsOfPagesWithNewsPlugin();
        if (empty($pagesWithNewsPlugins)) {
            return '';
        }
        foreach ($pagesWithNewsPlugins as $pageWithNewsPlugins) {
            $cacheDefinition[] = '  ' . $pageWithNewsPlugins . ' := addToList(' . $newsStoragePIDlist . ')';
        }
        $cacheDefinition[] = '}';
        return implode(PHP_EOL, $cacheDefinition);
    }

    protected static function getIdsOfPagesWithNewsPlugin(): array
    {
        $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable('tt_content');

        $records = $queryBuilder
                ->selectLiteral('DISTINCT pid')
                ->from('tt_content')
                ->where(
                    $queryBuilder->expr()->eq('list_type', $queryBuilder->createNamedParameter('news_pi1'))
                )
                ->execute()
                ->fetchAllAssociative();
        return array_column($records, 'pid');
    }

    protected static function getPageIdsOfNewsStorageFolders(): array
    {
        $queryBuilder = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable('pages');

        $records = $queryBuilder
            ->select('uid')
            ->from('pages')
            ->where(
                $queryBuilder->expr()->eq('module', $queryBuilder->createNamedParameter('news')),
                $queryBuilder->expr()->eq('sys_language_uid', $queryBuilder->createNamedParameter(0, \PDO::PARAM_INT))
            )
            ->execute()
            ->fetchAllAssociative();
        return array_column($records, 'uid');
    }
}

@tgaertner pointed out $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['tslib/class.tslib_fe.php']['get_cache_timeout'] could be used instead.
@DanielSiepmann pointed out $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['Core/TypoScript/TemplateService']['runThroughTemplatesPostProcessing'] could be used instead.

I haven't tried it with those hooks yet, but both look promising and I might switch.