Heh, fair enough. The branding is just meant to be silly (and to make fun of misleading benchmarks) but I totally get how it might be off-putting to some.
FWIW the Cap'n Proto C++ implementation ought to be able to layer on top of vsock pretty easily. You can pass an arbitrary kj::AsyncIoStream to capnp::TwoParty{Client,Server}, and you can construct an AsyncIoStream wrapping any socket file descriptor.
But yeah, capnp RPC is definitely one of the more complicated RPC implementations out there and if you don't need that power it may be too much.