Api/v0/oxidized Only Yields 3 Fields

From the doco (which looks maybe a touch old): Devices - LibreNMS Docs

That function is here, and matches exactly what you see:

The query in that code pulls many other fields you could add to the output in the $output structure.

I don’t know what the convention is with all these, but you could add all the relevant ones and submit a pull request to start the discussion so others can benefit from your changes too.