I’ll check out the TPM, but our big draw with the Enclave system is being able to run general purpose code (Python / Go) inside a secure isolated environment. The earlier system we had was SEE machine on a HSM and required a special compiler to run - I haven’t seen the Nitro TPM just yet, but I doubt I’d be able run a container inside the boundaries of the TPM.
In case it's helpful: I'm maintaining a tool kit that makes it possible to run unmodified, general-purpose code inside Nitro enclaves:
https://github.com/brave/nitriding