You can add many layers of indirection, but unless you're actually authenticating that a system service is using the credentials (and not, say, a user or a script) then it boils down to a long-lived token at the end.
You can condition IAM on Nitro attestation, so that's doable (if a lot more work than usual).
You can condition IAM on Nitro attestation, so that's doable (if a lot more work than usual).