Great question — answering as the UphillTech team:
No you can't . In Shopify you buy the variant, which is passed using the variant ID. The SKU is text that can be managed by the admin, so it can be the same for all your products if you like, this means that it's not an unique value in any way.
Full answer by drip: https://stackoverflow.stackexchange.com/a/56471809 (CC BY-SA 4.0).
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