It doesn't, at least not for generic/unmodified cryptographic applications.

WebAuthN signatures are of a very specific challenge/response format [1] that applications need to explicitly support. For example, SSH had to add new key and signature formats [2] to support it.

Theoretically, a blockchain/cryptocurrency application could adopt the WebAuthN signature format as its canonical or an alternative signature format, but I'm not aware of any popular one having done so.

[1] https://developers.yubico.com/WebAuthn/Concepts/Using_WebAut...

[2] https://github.com/openssh/openssh-portable/blob/master/PROT...