Sorry for the delay in my reply here @zaragoza.susana! I’m happy to help offer some further assistance here.
1. The product I am selling has variations in terms of sizes, and I want to know if I need to list each size in a separate column in a Google Sheet.
Looking at that loom video it seems like it was giving an example of how to use it to search for a product not a product variant. To use a Google Sheets Lookup Spreadsheet Row action to search for a product you want to have a each different product variation (product size) in a different row rather than have multiple columns for each size variation.
That said, the Shopify app on Zapier has Find Product Variant by Title and Find Product Variant by SKU search actions available so it might be better to use one of those to look up the relevant product details that you want to have added to the order.
3. Should I include the SKU provided by the supplier both within the funnel and also in the Shopify section in Zapier?
That depends, does the SKU provided by the supplier match up with what’s used in Shopify? If not you might need to create a lookup table to convert the supplier’s SKU into the corresponding Shopify SKUs. You could use a Google Sheet like the one shown in that loom video to create a lookup table by having a column in the spreadsheet for the supplier’s SKU and the corresponding Shopify SKU.
Otherwise if you’re able to get the name of the product variant from ClickFunnels then you could just use a Find Product Variant by Title (Shopify) action to find the product variant’s details along with it’s SKU to add to the order details if desired.
Hope that helps. If you get stuck on that at all or need me to clarify anything further do let us know! 🙂