wildcard authorized principal?

[Peter Moody]

I suspect the answer to this is no, but say I have a setup where I
have a server with a shared user account and I want anyone with a
valid cert to be able to use that shared user. Is there a wildcard
AuthorizedPrincipal I can specify in my sshd_config to mean, "any
user"?

Alternatively, is there a way I can see the valid principals that the
incoming cert has in the AuthorizedPrincipalsCommand? It didn't appear
to be possible with the available TOKENS.

I would like to not have to enumerate every possible user because the
posix accounts don't exist on this shared machine and getting a
complete list of principals should be unnecessary considering our
certificate authority has validated the user(s)

Cheers,
peter