There are several metrics APIs depending on the object you are interested in. For example, if you want to see IOPs on aggregates, you could use the GET /storage/aggregates/{uuid}/metrics endpoint or for luns would be GET /storage/luns/{uuid}/metrics. These endpoints existing for clusters running ONTAP 9.7 or above.
You can see from the URL that they require asking about a specific object. There is no node level call that lets you summarize them all automatically. You could write your script to do this however. It might be something like this:
from netapp_ontap import HostConnection, config
from netapp_ontap.resources import Aggregate, PerformanceMetric
config.CONNECTION = HostConnection("1.2.3.4", username="admin", password="pass123", verify=False)
# get a list of all of the aggregate uuids on node1
node_name = "node1"
aggregate_uuids = [aggr.uuid for aggr in Aggregate.get_collection(**{"node.name": node_name})]
# for each aggregate, find its total IOPs and add it to the sum
total_iops = 0
for uuid in aggregate_uuids:
total_iops += sum([m.iops.total for m in PerformanceMetric.get_collection(uuid, fields="iops.total")])
print(f"Total IOPs for node {node_name} is {total_iops}")
This example uses the netapp-ontap library (download, docs).