Answer engines do not read your brand story. They read structured facts: attributes, specifications, availability, price, compatibility, reviews. Whoever has the cleanest facts gets quoted.
That makes generative engine optimisation a data project. A product with five populated attributes and a clear title outperforms a beautifully written page with an empty spec table, every time.
A migration is the cheapest moment to fix it, because you are already touching every record. Mapping into the Shopify taxonomy, filling metafields and normalising units costs almost nothing extra while the data is in motion, and it is expensive to do later by hand.
That is the reasoning behind Syncer Proof: compare your historical data against your new data after go live, then use the gap to decide what to fix next.