I had a need to pass an ID to my SKU. So I created a column in my google sheet. It is an array formula that picks up and joins two columns. AX is column with SKU and A2 is a unique Row ID.
=ARRAYFORMULA(if(AX2:AX <> “”, AX2:AX & “~~~” & A2:A, “”))
In addition, see this post if it is helpful.