Those JSON files are created using info from the pepper1db site. If your device is listed there, then a json file must be added to HG. At the moment, I'm not exactly sure how it is done programmatically, but I'm sure you could try and add the missing json file yourself. You could make a copy of a similar json file and fill in the values you need.
If your device specs are not in the pepper1db site, then this will be a bit more work along with some trial and error.
I don't remember the pepper1db site url at the moment, but you can find it on your module config page.