Custom widget code needed

Hi, we currently have this widget selection on Shopify that is our current winner and want to test that on funnelish.

No need to do the subscription section. Only need the variant picker + add to cart button.

We just need the variant picker selector to change the link of the add to cart button. We will use a unique checkout link for each option. Once selected and add to cart is clicked it will go to the respective checkout page.

Please let me know how to change the links for each variant.