Nitro enclaves is a lot less ambitious than this. This is a full blown microkernel. Whilst nitro Enclave is a Linux kernel with just virtio drivers enabled + a small initrd containing your Linux application. The "Trusted compute base" of nitro enclaves is larger.

Nitro enclaves also doesn't have all this high level infrastructure of composing microservices like this does

I think (but somebody smarter might correct me) that with nitro enclaves you also need to trust Amazon. Whilst with this you need to trust AMD, but don't need to trust GCP

Nice thing about nitro enclaves is that the Linux bits aren't tied to OCI. E.g. Monzo uses nix to build their enclave images https://github.com/monzo/aws-nitro-util