Snipcart

Snipcart is a shopping cart solution in itself. The Kart plugin does not ouput the HTML attributes required by Snipcart but you could do that in your templates.
Snipcart has no hosted checkout thus their JS library is used as described below.
You can use this provider to import products sold on Snipcart into Kirby and later switch to another provider for payment processing.

Using the provider

<?php

return [
   'bnomei.kart.provider' => 'snipcart',
   // other options
];

API Credentials

SNIPCART_PUBLIC_KEY=XXX
SNIPCART_SECRET_KEY=ZZZ

Snipcart Checkout JS

<?php snippet('kart/snipcart-checkout') ?>

<?php // or create a custom version based on the snippet ?>
<script>
  ...
</script>