Strict to 1 country only in checkout page with wordpress and woocommerce

Also maybe you want to sell to several countries but also you want to show ONLY the country where the user is connecting from (geolocated from IP address). Thus, in this way, a french user will only see France in the country dropdown, an australian user will only see Australia in the country dropdown and so on... Here is the code:

/**
 * @param array $countries
 * @return array
 */
function custom_update_allowed_countries( $countries ) {

    // Only on frontend
    if( is_admin() ) return $countries;

    if( class_exists( 'WC_Geolocation' ) ) {
        $location = WC_Geolocation::geolocate_ip();

        if ( isset( $location['country'] ) ) {
            $countryCode = $location['country'];
        } else {
            // If there is no country, then return allowed countries
            return $countries;
        }
    } else {
        // If you can't geolocate user country by IP, then return allowed countries
        return $countries;
    }

    // If everything went ok then I filter user country in the allowed countries array
    $user_country_code_array = array( $countryCode );

    $intersect_countries = array_intersect_key( $countries, array_flip( $user_country_code_array ) );

    return $intersect_countries;
}
add_filter( 'woocommerce_countries_allowed_countries', 'custom_update_allowed_countries', 30, 1 );