This is Noise NK, possibly with differences in the hashing details which I did not check:

https://noiseprotocol.org/noise.html#interactive-handshake-p...

I encourage you to use their hashing details. They're battle-tested.

Wireguard uses Noise IK, which is NK plus a static public key for the initiator which is encrypted to the agreed-upon-session-key without adding additional round trips. Your protocol and Noise NK omit the parts related to the initiator's static public key, because it has none.