There is a complete OEM carbon Ceramic brake setup right now on Ebay.

MERCEDES C190 AMG GT / GTS / GTR / CARBON CERAMIC BRAKE CALIPER CALIPERS SET OEM | eBay

I know I saw at least one thread in the past with someone looking for one.

 

Thx for pointing out.

Are there any software/flash changes needed to swap?

 

That's a good question. I don't know. If there is, it would be because the rear parking brake motors are different than on a GT, but from a visual, the rear calipers look identical.

 

Looking at the ceramics in a bigger pic, now back to thinking they're the same calipers. But still think the bracketry might be needed.

 

Those are simple bolt-ons but will likely require different brackets (bolts, etc.) for a GT as they have a slight different brake setup than the GTS.
Please note one rotor is chipped and pics don't show both sides in detail. I would request detailed pics of every rotor from both sides and wear marks. The chip shouldn't be a big deal but a dealer will tell you to swap the rotor for safety reasons...

 

I dont see where the parking brake actuator is on the calipers as well.

 

Actually two of them are chipped and one shows stress marks. The rotors appear to be poorly handled. I wouldn't consider getting them...

 

Found these but they don't look much better. MERCEDES C190 R190 GT GTR CARBON CERAMIC BRAKE KIT SET 2017-2020 FRONT AND REAR | eBay

 

A new set will set you back 12K. Ive priced it out via the same source I got my OEM wing from. Also, fun fact - these fit a lot of different cars - E, S, GT, SL, etc. Like Wolfman said too, you need some brackets. I havent confirmed, but I had heard from an MB tech that they do need to be coded to the car, but not sure why; might be the ABS.