Cash on delivery fee (αντικαταβολή)

<?php

// The fee before VAT (WooCommerce adds VAT to fees): with 24% VAT, 1.61
// becomes 2.00. Change the label if you like.
$fee   = 1.61;
$label = 'Έξοδα αντικαταβολής';

add_action(
	'woocommerce_cart_calculate_fees',
	static function ( $cart ) use ( $fee, $label ) {
		if ( is_admin() && ! wp_doing_ajax() ) {
			return;
		}
		if ( 'cod' === WC()->session?->get( 'chosen_payment_method' ) ) {
			$cart->add_fee( $label, $fee, true );
		}
	}
);

// Recalculate the totals when the customer picks another payment method.
add_action(
	'wp_footer',
	static function () {
		if ( function_exists( 'is_checkout' ) && is_checkout() && ! is_order_received_page() ) {
			echo "<script>jQuery( function ( $ ) { $( 'form.checkout' ).on( 'change', 'input[name=\"payment_method\"]', function () { $( document.body ).trigger( 'update_checkout' ); } ); } );</script>";
		}
	}
);