I remember sites doing all sorts of hacks to identify and shut down IE back in the day. "Works best in Chrome/Firefox".
"The proposal calls for at least the following information in the signed attestation:
The attester's identity, for example, "Google Play".
A verdict saying whether the attester considers the device trustworthy.
"So a user agent string and a weak attestation?
This seems an overcomplex nothingburger.
Is that listed in the article anywhere? Is that part of the proposal?
The proposal does however say that even if the attestation fails, that the user should be allowed to access the website.
Are you upset with the proposal, or some other proposal that you are imagining?