Such plugins only collect metrics available via api or other interfaced that can be reached by OneAgent plugin or ActiveGate plugin. In general if you are able to find way to collect some extra metrics you will be able to collect extra data. You have to check first IBM documentation and check what option for gathering metrics are available. For API call you can create ActiveGate plugin, for bash/cli etc. OneAgent plugin. Both of them will use custom metrics for storing data. If you will need OneAgent plugin you will have to cover this machine with DT license at least for infrastructure mode. I don’t think that it is possible to instrument this process in another way.
This plugin is storing fetched metrics as custom metrics, so you can use timeseries api for consuming them. About how it looks on IBM side you have to go to their docs I think.
As I see here it’s ActiveGate plugin so it is using some available interface on DataPower side for fetching data. There should be doc about it.