Weirdly, the port on a cheap mechanical keyboard I have is USB-C but the cable they packaged is USB-C -> USB-A instead. They likely didn't package C->C because of the chicken and egg problem. Not everyone has enough Type-C ports.
I built my own based on a USB 2.0 hub IC, but I never got around to publishing the design files. I should get on that!
Even building a single prototype unit cost me about the same as a single off-the-shelf type-C hub, but of course, building subsequent units would be substantially cheaper.
Meanwhile the most frequent complaint I read about USB-C is trickster/confusing cables or hubs because they don’t support everything
1: the four USB-C ports it provides aren’t enough for my use; one is occupied by Apple’s USB-C DAC (the Framework’s 3.5mm port is unusably noisy with my Shure IEMs). Then add my charger, tethered iPhone, and a peripheral like a mouse or drawing tablet, and you can see why I need a hub.
P.S. if you did release the files and it was a reasonably affordable DIY project (e.g some soldering and assembly), I’d love that. Although I guess you’d need to buy a fair number of all the components to bring the price down.
I've also noticed there are next to no usb-c hubs, apart from "docks" that usually do many more things are bigger. But, don't they have to provide the specced power to be "compliant"?
What I find annoying is that even "higher end" docks don't have many usb-c ports. I'm typing this through a HP dock that has a big-ass power adaptor and is quite big and heavy itself (has a huge heatsink), yet it still provides only one usb-c port. At least it seems to implement PD (I can charge a laptop through the downstream port), even though I think it only provides 15W.