Right now Two Tap supports only domestic shipping, meaning a US retailer ships only to the US, UK one only to the UK and so on.
We did offer crossborder last year as a preview. It was a great learning experience, the most important lesson being that a reliable crossborder logistics solution is hard to find.
We’re close to signing an agreement with another provider, and should be up and running in 3-4 months.
Meanwhile, you can use Two Tap + your own crossborder provider (eg myUS). The TT WooCommerce might also be of help: