And Azure doesn't support it while instantiating a VM. Which boggles my mind since AFAICT all they have to do with the key material I hand them is to copy it in

And Azure doesn't support it while instantiating a VM. Which boggles my mind since AFAICT all they have to do with the key material I hand them is to copy it into authorized_keys, not inspect it and tell me my valid key is invalid.