I wonder if suggesting dozens of hardcore crabon track bikes is helpful to a person looking for
a single speed carbon bike
Yeah, I guess that a track bike is essentially only a freewheel and some brakes from being a singlespeed but my money says the OP does not want anything like that. He wants the equivalent of a crabon roadbike with trackends and I can't think of anything off-the-shelf like that. And if anyone wants to look it's a subject that's been worked over here before with not dissimilar conclusions.
Good luck - let us know if you find anything...