Environment::getCountries() 

public function getCountries ( $lang = 'de', $key = 'cn_iso_2' ) {
	if (!ExtensionManagementUtility::isLoaded('static_info_tables')) {
		$countryProvider = GeneralUtility::makeInstance(CountryProvider::class);
		$allCountries = \nn\t3::Convert($countryProvider->getAll())->toArray();
		if ($lang != 'en') {
			$languageService = GeneralUtility::makeInstance(LanguageServiceFactory::class)->create($lang);
			foreach ($allCountries as &$country) {
				$country['name'] = $languageService->sL($country['localizedNameLabel']);
				$country['officialName'] = $languageService->sL($country['localizedOfficialNameLabel']);
			}
		}
		if ($key != 'cn_iso_2') {
			$results = array_column($allCountries, 'name', 'alpha3IsoCode');
		} else {
			$results = array_combine(
				array_keys($allCountries),
				array_column($allCountries, 'name')
			);
		}
		if (extension_loaded('intl')) {
			$coll = new \Collator('de_DE');
			uasort($results, function($a, $b) use ($coll) {
				return $coll->compare($a, $b);
			});
		} else {
			$oldLocale = setlocale(LC_COLLATE, 0);
			setlocale(LC_COLLATE, 'de_DE.utf8');
			asort($results, SORT_LOCALE_STRING);
			setlocale(LC_COLLATE, $oldLocale);
		}
		return $results;
	}
	$data = \nn\t3::Db()->findAll( 'static_countries' );
	return \nn\t3::Arrays($data)->key($key)->pluck('cn_short_'.$lang)->toArray();
}