You're totally correct and I've been looking into those precisely.
By looking at the documentation for Stan's Asset iOS Native, it turns out that in the very large amount of functionalities covered, there isn't any solution to collecting that kind of data, either in Native System Events or System Utilities.
As for U3DXT, I've been looking into it, there seems to be what I want, but it's pure code and apparently not of the simplest kind!
At least there seems to be descriptions about ways to gather values, subscribe to events (necessary too) and send data to Xcode's log.
Hitcent's free
iOS4Unity probably does something similar too.
But none of them have Playmaker actions ready to use.
In all cases, it seems I'm loking for data that belongs to the UIDevice category of things.
And, with this in mind, there would have to be some way of sending data to log so we could at least read what's going on in Xcode's log console, after a build is made and pushed onto the test device.
Whoever would produce those custom actions, they would certainly be a great public addition for the community at large!