Hi there @huoise,
Welcome to the Community! Thanks for sharing your question with us!
Yes unfortunately, the "Started Checkout" event used in abandon cart flows does not include variant information, which is why you can’t use it in flow filters as you’ve experienced. In order to do this you would need to make a custom event and make sure the variant info isn’t nested too deep that you can’t access it for flow filters. You will need to contact your developer or a Klaviyo partner to build this out for you if you don’t feel comfortable with custom coding.
However, depending on where your ‘Placed Order’ event has placed the SKU number in the data, you should be able to filter messages with flow filters or conditional splits in a ‘Post-Purchase’ flow for whatever version of your item a customer purchased!
Hope this helps!
-Taylor