We have built store in shopify and I use Google sheet to upload and update the catalogue product feed in Facebook for advertising purpose, instead of other method like using Flexify.
In the Google sheet, I use sku for id and shopify might use content id for id therefore I am receive matching rate message like this:
Not really, I replace the SKU numbers with content IDs in the feeding data
to match the product ID from shopify, we cannot edit the content id, I
think, which are owned by Shopify