How to checkout without a shopping cart?

Question

WordPress

Hello, here is the issue. I need to make it possible to place an order from a custom form, where there is only a phone number and a name. And after filling out this form and selecting a product in the select, immediately send it to the gateway. In general, the chip works, but as it turned out, because I was logged in. In the case of a normal user, the redirect goes to an empty cart via the checkout link. Tell me where to dig? I use the following code:

$variant_id = $_POST['count'];
        $address = array(
            'first_name' => $_POST['name'],
            'phone'      => $_POST['phone'],
        );
        $order = wc_create_order();
        $order->add_product(wc_get_product( $variant_id ), 1 );
        $order->set_address( $address, 'billing' );
        $order->set_address( $address, 'shipping' );
        $order->calculate_totals();
        update_post_meta( $order->get_id(), '_payment_method', 'rbspayment' );
        update_post_meta( $order->get_id(), '_payment_method_title', 'Альфабанк' );
        WC()->session->order_awaiting_payment = $order->get_id();
        $available_gateways = WC()->payment_gateways->get_available_payment_gateways();
        $result = $available_gateways[ 'rbspayment' ]->process_payment( $order->get_id() );
        
        if ( $result['result'] == 'success' ) {
           echo $result['redirect'];
            exit;
        }
        exit;

I send the form with Ajax, and if I am authorized, it throws me into the gate, if not, into an empty basket, with an additional message saying that your basket is empty, there is nothing to pay.

Answer 1

Issue resolved.
Added:

global $woocommerce;
$woocommerce->cart->add_to_cart(id товара);

Before create order.
Now everything worked as it should. Like

Answer 2

WC()->session->order_awaiting_payment = $order->get_id();
        $available_gateways = WC()->payment_gateways->get_available_payment_gateways();
        $result = $available_gateways[ 'rbspayment' ]->process_payment( $order->get_id() );

WC()->session->there's a problem!