For AEM as a Cloud Service you have a CDN by default (Fastly), so for CDN hits/misses you can check the x-cache header (see [1]).
In case of CDN misses the next layer is the AEM dispatcher, which is fully under your control. IIRC the vhost blueprint adds a "x-vhost" header to the response (mostly for debugging), but it does not indicate if it's a hit in the dispatcher cache.
Dispatcher cache misses are handled by AEM itself, so you could add a special header (which is not cached on the dispatcher, in case you have enabled header caching) to indicate that.
But in general AEM/dispatcher is not verbose when it comes to indicate if a request was a cache hit or not. Because it could also be misused. But of course you can add all by customization.
[1] https://developer.fastly.com/reference/http/http-headers/X-Cache/
