@DavidT Same problem, same disappointment here. The experience with the REST API was flawless, but this forced migration without a proper migration path is incredibly frustrating. It feels like they don’t care about developers in this situation. Have you managed to find a solution?
I’ve created a thread in the hopes that Shopify will at least provide a clear guide on how to address this issue => How To Safely and Efficiently Sync Products and Inventory Using ProductSet Mutation?