Mutual certs get you closer, but the missing component is device state validation. I probably don't want to share my understanding of device state with a third

Mutual certs get you closer, but the missing component is device state validation. I probably don't want to share my understanding of device state with a third party (it might include things like which apps are installed on a device, and sharing that with a third party is extremely not cool), and I probably don't want to share my policy (if they get popped then an attacker is going to be able to figure out what I'm looking for), so I need a mechanism where the third party can call out to me with proof of the client identity and I can then compare that against my policy and give an answer back. And we don't have a good way to do that yet.