The C-One currently does not have a C64 core (i.e. it doesn't emulate a C64), and it might take a while until it gets one, as the person that should have originally provided it is not able to do so.
(that info is a few months old, if there's news regarding this I have missed it)
A SuperCPU is extremely hard to come by. Maurice Randall (the guy who has the rights to produce them) was busy with his real life for quite a while and didn't accept orders. I think he announced that things have changed for the better, but by now he must have an extremely large backlog of waiting orders.