alt Hacker NewsThat is what remote kvm are for and if you do that on commodity hardware you can start a tiny ssh server starting up from an initrd. Having said that an attacker with local access could change the initrd without your knowledge so that it logs the password you enter so it is not necessarily the most secure solution.
You’ve answered it yourself. Without TPM you have no idea if you can provide the secret to the system or if it’s compromised. Whether that secret comes from TPM or network is secondary.