But thats exactly how it doesn't work - you are referring to Software-level TPMs. I.e. the SecureEnclave in iPhones work in a way that you can always put keys I

But thats exactly how it doesn't work - you are referring to Software-level TPMs. I.e. the SecureEnclave in iPhones work in a way that you can always put keys INTO the TPM chip, but cannot read it out back later, but rather have the SecureEnclave perform the crypto on chip (requiring some form of authentication, like a fingerprint read or a button press on Yubikeys). Even a full-root access should not compromise that.