@nvandable , maybe it is still relevant, as I needed to cope with the same issue: I think it is best to work with a “orders” sheet, let users configure new orders, add a row for every new order, concatenate in gsheets to make a complex SKU, and add a buy button to place a new order.
With user specific columns you run into even more problems. like this: “Item No Longer Available” Buy Button issue - Glide Community (glideapps.com)