Since Ed* keys can only be used for signatures (and have one dedicated JWS "alg" identifier) and X* can only be used for ECDH (meaning not the WebCrypto algorithm identifier here) the following operation steps should be added. The alg ones I think for sure, the use ones I'll leave to a discussion.

Ed25519 JWK importKey operation

Add a step

If the alg field of jwk is present and not "EdDSA", then throw a DataError.

Ed448 JWK importKey operation

Add a step

If the alg field of jwk is present and not "EdDSA", then throw a DataError.

Ed25519 JWK exportKey operation

Add steps

Set the alg attribute of jwk to "EdDSA".
Set the use attribute of jwk to "sig".

Ed448 JWK exportKey operation

Add steps

Set the alg attribute of jwk to "EdDSA".
Set the use attribute of jwk to "sig".

X25519 JWK exportKey operation

Add a step

Set the use attribute of jwk to "enc".

X448 JWK exportKey operation

Add a step

Set the use attribute of jwk to "enc".