Running into the exact same issue - have configured nginx_status location and can pull data via wget in the example posted however the agent is not pulling this information nor is it possible to execute the plugin independently receiving the name NameError.
What kind of information will you require for further troubleshooting? Is there a specific version of python3 required?
root@df /usr/lib/check_mk_agent/plugins ./nginx_status
Traceback (most recent call last):
File “./nginx_status”, line 43, in
@get_parsed_item_data
NameError: name ‘get_parsed_item_data’ is not defined