Q: Can sku grid detect supplier shipping for items where shipping is determined at checkout or not?
A: Sku grid cannot determine the shipping if the store uses Calculated Shipping. Typically, sku grid can only know the shipping amounts that are known on the product pages, or if the company has Flat Rate Shipping (i.e. $5.99 shipping for items under $45) or if they have Tiered Shipping ($5.99 shipping for items between $1 - $29.99, $6.99 shipping for items $30 - $49.99, $7.99 shipping for items $50 - $100 and so on) In those cases, sku grid can usually detect shipping.
However, for stores where shipping is not known until you add to cart and go through checkout as shipping is determined by the weight of the product and where it is going, it is not possible for sku grid to know or see that.
If you add the item to cart to determine the approximate shipping, yes you can override the item, fill in all other appropriate formula values and put in the shipping amount into both the fixed and minimum margin fields as explained in the video on using stores that have calculated shipping - CLICK HERE