We indeed integrate with CAPI, but the OS itself is not a CAPI implementation. We have a CAPI provider that works hand-in-hand with the OS.
I am not sure that you want to call it an OS per se, since kubernetes itself is the OS (manage memory, schedule processes, etc).
So there is no default CAPI provider?
Perhaps OS isn't the right thing to call, but I don't know a better alternative :D