Valid categories and keys for getSystemSettings

Evidently the getSystemSettings service call will fail unless a valid key is specified. Is there a way of obtaining a list of all of the valid categories and keys accepted by this service call?

You can find all available keys in getSystemSettings. Thank you.

I found info elsewhere on how to obtain some of the picture settings, e.g. “category”: “picture”, “keys”: [“contrast”, “backlight”, “brightness”, “color”]
Is it possible to obtain all of the other picture settings, as well as other settings? This info does not appear to be on the doc page you pointed me to.

Currently, we only provide the keys in the document. If there are any updates, we will let you know via our website. Thank you.