You should be able to write your own Oneagent plugin retrieving metrics from Perfmon. You even should not need Python for that. You just need to write a correct plugin.json file describing metrics to be received and charts to be displayed.
I didn't try it, but according the ruxit.perfmon.dotnetV4/plugin.json that is available in the Windows OneAgent (in the agent\plugins directory) this should not be difficult.
The plugin.json reference is here https://dynatrace.github.io/plugin-sdk/api/plugin_json_apidoc.html