Life is easier if you can use Kerberos SSO, i.e. GSSAPIAuthentication in OpenSSH. (If we're talking certificates, presumably it is OpenSSH, or does anything else implement them?)
You have to manage extra infrastructure for certificates and, as a user, have the friction of firing up a JavaScript-enabled web browser via an additional tool, assuming "real IdP" means using OIDC. Unfortunately that flow is actually needed for remote systems and something like Edugain federation, since Moonshot/IETF ABFAB failed, but at least Shibboleth can use the TGT, and it's not the Globus horror.
Setting up Kerberos in 2026 feels somewhat close to malpractice to me.
> Setting up Kerberos in 2026 feels somewhat close to malpractice to me.
Microsoft (if that means anything, but they've done good work) and Red Hat obviously disagree, along with decades' experience. It is malpractice not to secure NFS mounts (and other network filesystems with sensitive data), and that means Kerberos.