AMD and Microsoft have since confirmed that the Ryzen Surface Edition processors are custom versions of the Ryzen 5 3500U and Ryzen 7 3700U, and now examples of the former have appeared on UserBenchmark. While the Ryzen 5 3580U fares well compared with the Core i5-8265U, it appears to fall short of the Core i5-1035G7 in multi-core workloads.
https://www.notebookcheck.net/AMD-Ryzen-5-3580U-disappoints-in-early-benchmark-results-averages-13-less-than-the-Intel-Core-i5-1035G7-in-multi-core-workloads.436849.0.html