As far as I know, you have never been able to import or export keys from the Secure Enclave. It’s more likely that previously keys were stored in the keychain and now they are generated in the SE by default.
Yes you can make private keys that are encrypted by the secure enclave, rather than stored inside it. The "sc_auth" tool on macos has a "ssh-exportable" variant
Yes you can make private keys that are encrypted by the secure enclave, rather than stored inside it. The "sc_auth" tool on macos has a "ssh-exportable" variant