Wireguard is more or less just Noise (IK I think) for IP packets. It wouldn’t make much sense for files since there is no counterparty. File encryption is done differently.
Noise has one-way handshake patterns for things like file encryption, but the pattern implemented by Wireguard is an interactive one. Compare sections 7.4 and 7.5 in the spec.
Edit: http://noiseprotocol.org/