In reply to Tolis.

Third-party gateway support is possible, however, developers will need to integrate it, if you’re a third-party payment gateway developer, you can read the integration guide:

https://github.com/woocommerce/woocommerce-gutenberg-products-block/blob/master/docs/extensibility/payment-method-integration.md

The API is fairly stable, if you intend to integrate, keep an eye on the WooCommerce developer blog for updates.