Been about 8 years that I have struggled with front panels on my cases that have two Type-C ports but only one header on the motherboard that would support either of those ports.
It first started with the Corsair 900D case - now I have purchased the Corsair 1000D case and again with the two USB-C on the front panel but only enough support on the motherboard for one of them.
I went searching for a PCIe card with even just one header to support the second and could not find any. Finally found one from Ableconn.com but I have never heard of them and the reviews aren’t helping.
Keep in mind, though, the above card doesn’t appear to support power delivery so the card would not be adequate for me.
My question is why hasn’t Startech made anything at all to support this? Been a long time fan of Startech’s Hard to find mentality cause I am a unique person with respect to computer builds. I was totally shocked to find they have nothing 
There are a ton of adapters being made by unknown brands but the thing with those are - it’s converting a USB3 connector to a USB Type-E and with that power issues come into play since USB3 won’t supply Type-C power consumption ability