Yes, as a general rule, that is possible. Any node on the Bristlemouth network can subscribe to any topic, and if another node (including Spotter) publishes info on that topic, then subscribers will receive it.
That said — and we were just discussing this the other day — Spotter does not currently publish any of the battery or solar panel metrics. The only topic that Spotter publishes at the moment is spotter/utc-time, and all the dev kit apps subscribe to that topic to set their RTC.
We recently added to the Spotter firmware backlog 3 features we’d like to implement at some point, publishing battery, location, and wave data to the Bristlemouth network. We’ve had requests for all of these from various customers.
As far as the API is concerned, the only historical view into hardware status information is through the CSV download from the dashboard. This allows downloading up to one month at a time.
I don’t have anything to add here other than it sounds very interesting to have a node be able to grab Spotter data perhaps as an alternative telemetry device (like WiFi or LoRA). I mostly replied to follow this topic since I’m really interested in it!