API for docking pos system.

What is the pos system you are talking about?

Never heard of but found this:
https://www.deliverect.com/en/integrations/woocommerce

WordPress itself does not provide connections to external APIs. This is handled by plugins that can establish such a connection on their own.

Then check out the link above.

Or ask in the WooCommerce suuport forum: https://wordpress.org/support/plugin/woocommerce/