Best answer: There is no USB-C or Thunderbolt 3 support on the Surface Pro 6, sadly. However, there are plenty of other great 2-in-1 tablet options for those that desire the functionality.
- Dell: Dell XPS 13 2-in-1 ($999+)
- HP: HP Spectre x360 ($950+)
Why is there no USB-C or Thunderbolt 3 on the Surface Pro 6?
Microsoft has been criticized extensively for not including high-bandwidth USB-C connectivity in either the Surface Pro or Surface Laptop lines for some time, thus far only including it in the Surface Book 2 and the Surface Studio 2. The reasons why it's not in the Pro 6 are similar to that of the Laptop 2; Microsoft tends to value its own proprietary Surface Connect port for additional USB, external monitors, and docking stations, such as Microsoft's own Surface Dock.
In the case of the Pro 6, the omission of Thunderbolt 3 is frustrating because the Pro 6 would benefit more than most devices from a dedicated external GPU, like the Razer Core.
USB-C and Thunderbolt 3 are more costly than regular USB to implement, particularly since it would require a shuffle of components for the Pro 6 and Laptop 2, which are incremental hardware updates for the most part. Eventually, Microsoft won't be able to ignore the proliferation of the tech, particularly now that Intel has scrapped the licensing fee for Thunderbolt 3 to help drive adoption.
The Surface Pro 6 is a stunning 2-in-1 device regardless, but if you desperately need USB-C and Thunderbolt 3, there are plenty of great alternatives to consider.
Best alternatives
Microsoft won't be able to ignore USB-C and Thunderbolt 3 forever, and while we wait for them to get on board with the big-bandwidth revolution, here are some 2-in-1 versatile Windows PCs with touch you should definitely consider.
Flip into tablet mode
Dell XPS 13 2-in-1
A 360 hinge for some tablet-style versatility.
Dell's updated XPS line now includes 2-in-1 options complete with a 360 degree hinge for tablet usage. It doesn't support the Dell Active Pen for digital inking, but for quick annotations and signing documents the ten-point touch screen should be more than adequate. This a laptop that is sleek, powerful, and quite affordable, complete with Thunderbolt 3 support.
The Dell XPS 13 2-in-1 is a pretty and powerful device, and the inclusion of Thunderbolt 3 increases its versatility immeasurably. However, if you want a device that can do all of that as well as inking, take a look at the HP Spectre x360.
Go 360 degrees (with inking)
HP Spectre x360
360 hinge with inking chops
If you want Thunderbolt 3 in addition to inking, consider the HP Spectre x360. It's powerful and versatile with a 360-degree hinge, making it as portable as it is productive.