Hi Jai,
I know I updated you regarding this in your ticket with us, but I just wanted to update this forum post for anyone following it.
This action has been implemented already! Feel free to try it out and let us know if you encounter any issues with it.
Send us a ticket, we will try our best to assist you with your problem
Jai Li
For Shopify, why the action to "Create Product Variant" is not available