Error / feature-request: Signing git commits with SSH hardware key

Hi!

I noticed git commit signing works well with ssh-ed25519 keys, but does fail with sk-ssh-ed25519@openssh.com SSH hardware keys (with can be used to clone / post to github for instance).

Would that be possible to support in a later release? Thus having a smart card can be useful for both ssh and git.

I also noticed a similar error in a previous mail from Cuckoo Aidan <aidancuckoo@gmail.com>, but he doesn't say which type of key he used. In any case, would that be possible to include the info about which type of keys cannot be used to commit in the github guide https://docs.github.com/en/authentication/managing-commit-signature-verification/telling-git-about-your-signing-key#telling-git-about-your-ssh-key) ?