Reddit mentions of ULANSeN USB 3.1 Type E PCI-E to USB 3.1 Type C Female Gen 2 Extension Cable with Profile Bracket

The only 19 Pin to 20 Pin USBC Front Panel converter we know of

Comined with this:

USBC Front Panel Male to USBC Female

Keep in mind every USBC port contains TWO high speed signal lanes, this will be used for USB 3.2 2x2 20Gbps (When it comes out) and currently used for alt mode.

It's far better to use actual USBC logic / chipset. The above adapter will only give you 900mA, and MAYBE BC1.2 of 1.5A. But a true USBC add in card (AIC) will give you 5V at 3A MINIMUM. a good one can do 9v, 12v,15v,20v all the way up to 20V/5A or 100W. On top of that there is alt modes, protection circuitry, a host of other things.

Just converting USB 3.0 19 Pin headers (2 USB 3.1 Gen 1 Ports) into a single front panel USBC gives the MINIMUM functionality. So it's practically pointless. The ONLY thing you are getting, is the ability to use a USBC to USBC Cable. Nothing else. If you are going to spend money, why use the onboard chipset, which is already saturated because you are using the other ports. Faster and better in every way to get a PCIe card.

Use one of these instead:

UGREEN USBC AIC like 20 bucks

This will get you 5V 3A Charging.

If you want full Power Delivery Profiles up to 100W, that's a tough story. Basically these days, people go with Thunderbolt 3 if they want PD 100W. If it's USBC, the only one I know of is OLD, and only works with SATA Express, which has been largely abandoned.

HERE