I am trying to populate a custom field called Customer Type in checkout with the current user role. I tried the below in my functions.php of my child theme and thought it would work but it does nothing. Can anyone tell me what I might be doing wrong?

$user = wp_get_current_user();
function onboarding_update_fields( $fields = array() ) {

   $fields['customertype'] = $user;

return $fields;
}

add_filter( ‘woocommerce_checkout_fields’, ‘onboarding_update_fields’ );