gistfile1.txt

    public static function getCountryOptions(string $locale) : array
    {
        $resourceBundle = ResourceBundle::create($locale, 'ICUDATA-region');
        $options = [];

        foreach ($resourceBundle['Countries'] as $countryCode => $label) {
            if (!preg_match('(^[A-Z]{2}$)', $countryCode) || 'ZZ' === $countryCode) {
                continue;
            }

            $options[$countryCode] = $label;
        }

        $collator = new Collator($locale);
        $collator->asort($options);

        return $options;
    }