To obtain a report from LM of datasources and how many devices are using those datasources.

Same. Although I used the SDK (references my custom lm library) 

from lm import lm
from pprint import pprint
devices = lm.get_device_list(size=1000).to_dict()['items']
result = {}
for d in devices:
    datasources = lm.get_device_datasource_list(d['id']).to_dict()['items']
    for ds in datasources:
        # print(f"{d['display_name']}: {ds['data_source_display_name']} ({ds['instance_number']})")
        if d['display_name'] in result:
            result[d['display_name']] += ds['instance_number']
        else:
            result[d['display_name']] = ds['instance_number']
for k,v in result.items():
    print(f"{k}: {v}")