[SahAssar]

Those have been broken again and again. Even if not, how do you distribute the public keys for it, how do you bootstrap that trust?

[rwmj]

Confidential computing is a whole thing with a key in each processor and a chain of trust and a way to remotely attest that your software is running in a secure enclave. All the vendors do it differently (sadly) but it's very much a solved problem.