They'll "give" you a USB-C dongle.
https://www.theverge.com/2017/5/23/15674254/microsoft-surfac...
> Microsoft is planning to release a dongle that will plug into the new Surface Pro and Surface Laptop devices and provide USB-C support. It’s like any dongle you’d expect, and it simply slots into the Surface connector port on the device. “If you want to charge a device with a Type-C charger, you can. If you want to put data back and forth with a Type-C peripheral, you can,” says Panay.