[Frontend Snippets] Change the default country on the checkout (non-existing users only)

wc-change-default-country-non-existing.php

/**
 * Change the default country on the checkout for non-existing users only
 */
add_filter( 'default_checkout_billing_country', 'change_default_checkout_country', 10, 1 );

function change_default_checkout_country( $country ) {
    // If the user already exists, don't override country
    if ( WC()->customer->get_is_paying_customer() ) {
        return $country;
    }

    return 'DE'; // Override default to Germany (an example)
}