Attestation always involves a "document" or a "quote" (two names for basically a byte buffer) and a signature from someone. Intel SGX & TDX => signature from intel. AMD SEV => signature from amd. AWS Nitro Enclaves => signature from aws.

Clients who want to talk to a service which has attestation send a nonce, and get back a doc with the nonce in it, and the clients have somewhere in them a hard coded certificate from Intel, AMD, AWS and they check that the doc has a good sig.

Yes, though I see the term abused often enough that it's not enough for me to believe it's sound just from the use of the term attestation. Nowadays "attestation" is simply slang for "validate we can trust [something]". I didn't see any mechanism described in the article to validate that the weights actually being used are the same as the weights that were hashed.

In a real attestation scheme you would do something like have the attesting device generate a hardware-backed key to be used for communications to and from it, to ensure it is not possible to use an attestation of one device to authenticate any other device or a man-in-the-middle. Usually for these devices you can verify the integrity of the hardware-backed key as well. Of course all of this is moot though if you can trick an authorized device into signing or encrypting/decrypting anything attacker-provided, which is where many systems fail.