Thanks @Paige-Shopify, I appreciate that.
We have battled an increasing number issues over the past year related to the POS cart properly validating or accepting newly-created product/variants. In a couple POS versions, this method stopped working entirely across the board.
And there’s been another breaking change in the past related to Catalogs / Markets: Can't add API-created product to POS cart affecting specific merchants - #6 by AndyC
Also, not sure if this is due to the Product Admin API => GraphQL migration or something else that changed behind the scenes over the past year, but during busier times merchants report unacceptably long waits for programmatic product/variant creation (8+ seconds in some cases).
Cart Transform eliminates many of the above issues, as we are simply adding the original product to the POS cart. Hopefully this helps.