Short answer
Yes. Once you import a Shopify metafield and map it to a column, that data becomes part of your Triple Whale data, and Moby can use it to answer questions, including combining it with your other sales and customer data. This works the same way for Customers, Orders, and Products metafields.
Context
For example, once a customer age metafield is imported, you can ask Moby to break down sales by age group for a specific product category, and Moby will build that answer using the imported column, joining it to your order data automatically. The same applies to an imported product metafield, like a material or rating field, or an order metafield, like a PO number.
Keep in mind that if a metafield was only recently added, many existing customers, orders, or products may not have a value populated yet. Moby's answer will reflect only the records that do, and a well-built answer should call that out rather than imply full coverage.