But if we take underscore package as standard, you can always get keys by calling _.keys(myJSONObject) .
Creating your own helper with needed functionality should not be problem than.
You can only perform an {{each}} on a cursor or array, [{},{},…]. Not a json object of json objects, {{},{}…}.
But an array of json objects is fine! Not sure why, but I also never looked too deep.
Once looping thru an an array, the json value can be called by {{key}}.
Best practice just convert your json object of json objects to an array of json objects, then do {{each}} on it.
If you want to print the key and the value, write a helper to get the key from the json and return the exact string, or a new data context for you template that would print it.