JSON that includes Device Features?

Have you looked at just using "has" and in cases do null checks? 

if has check works, then there's the debug xml in each device's folder. I use this python code to generate monkey.jungle files:

def has_method(dev, method):
    found = False
    if '.' in method:
        (clazz, func) = method.split('.', 2)
        searchFor = f'name="{func}" parent="{clazz}"'
    else:
        searchFor = f'symbol="{method}"'
    found = open(f"{SDK_DEVICES_DIR}/{dev}/{dev}.api.debug.xml", 'r').read().find(searchFor) != -1
    return found

dev is the device name (as the directories in Devices/ folder), method can be either in the "bar" or "Foo.bar" format (the second is better, in case the string "foo" can be found in other places in the xml, but the Foo.bar format only works if the parent="Foo" is present in the xml, so you need to check it before you decide which one to use.