Fine? The spec is not enough to implement the protocol. Right now, it's not meant to be implemented from its spec. The spec documents what the protocol is doing, because you want to know that in order to analyze it. It's not meant to facilitate clean-room interop.

WireGuard isn't an IETF protocol. In fact, it's a repudiation of IETF protocol design.

Right now, you should use WireGuard implementations Jason endorses, and avoid implements he expresses concerns about.