This extension is a backport of the country features from TYPO3 v12 to TYPO3 v11 + 10. Read all about it at https://github.com/TYPO3/typo3/blob/main/typo3/sysext/core/Documentation/Changelog/12.2/Feature-99618-ListOfCountriesInTheWorldAndTheirLocalizedNames.rst
Either use composer req georgringer/country-backport
or download the extension from the TER
Use this extension as in the core but with different namespaces:
<html
xmlns:country="http://typo3.org/ns/GeorgRinger/CountryBackport/ViewHelpers">
<country:form.countrySelect
name="country"
value="AT"
sortByOptionLabel="true"
prioritizedCountries="{0: 'DE', 1: 'AT', 2: 'CH'}"
/>
</html>
$countryProvider = GeneralUtility::makeInstance(\GeorgRinger\CountryBackport\Country\CountryProvider);
$france = $countryProvider->getByIsoCode('FR');
// or
$france = $countryProvider->getByName('France');
// or
$france = $countryProvider->getByAlpha3IsoCode('FRA');
// or
$filter = new \GeorgRinger\CountryBackport\Country\CountryFilter();
$filter->setExcludeCountries(['DE', 'AT']);
$filter->setOnlyCountries(['FR', 'IT', 'AT']);
$list = $countryProvider->getFiltered($filter);