Support SSH CA Certificates as authentication

I have switched from usual PublicKey authentication to Certificates.

Would it be possible to add support for this in WinSCP?

This request has been added to the tracker:
Issue 1873 – Support for OpenSSH certificates for user authentication

Are you using the certificates for user authentication only? Or also for verifying the hosts?

Both, we have different Certificates to sign the Host/Userkeys.

Thanks for your feedback.
I have filed a separate entry for host verification:
Issue 2145 – Support for OpenSSH certificates for host verification