selfLink not work for sys/hardware

As Niels said, you need to strip off the

chassis-power-supply-status-index

!/usr/bin/env python3

import pprint
import requests

requests.packages.urllib3.disable_warnings()

s = requests.Session()
s.auth = ('username', 'password')

r = s.get('https://hostname/mgmt/tm/sys/hardware', verify=False)

pprint.pprint(r.json())

You can deduce this by looking at the TMSH command to pull this information:

tmsh show sys hardware

chassis-power-supply-status-index

But once you have the JSON you can pull the info directly from there.