arista@devbox:~$ cat t3.py 
"""
pygnmi script
"""
from pygnmi.client import gNMIclient

TELEMETRY_REQUEST = {
                         'subscription': [
                             {
                                 'path': '/inventory/state/device/device-id'
                             }
                         ],
                         'mode': 'once',
                         'encoding': 'json'
                     }

with open("token.tok") as f:
    TOKEN = f.read().strip('\n')

if __name__ == "__main__":
     with gNMIclient(target=('192.168.0.5', '443'), token=TOKEN, skip_verify=True) as gconn:
         inventory = gconn.subscribe2(subscribe=TELEMETRY_REQUEST)
         for device in inventory:
                print(device)
arista@devbox:~$ 

arista@devbox:~$ pip install pygnmi==0.7.5

arista@devbox:~$ python t3.py 
ssl_target_name_override is applied, should be used for testing only!
{'update': {'update': [{'path': 'inventory/state/device[device-id=leaf4]/device-id', 'val': 'leaf4'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=host2]/device-id', 'val': 'host2'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=spine1]/device-id', 'val': 'spine1'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=leaf2]/device-id', 'val': 'leaf2'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=leaf3]/device-id', 'val': 'leaf3'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=spine2]/device-id', 'val': 'spine2'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=host1]/device-id', 'val': 'host1'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=leaf1]/device-id', 'val': 'leaf1'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'update': {'update': [{'path': 'inventory/state/device[device-id=cvx01]/device-id', 'val': 'cvx01'}], 'timestamp': 1658653200000000000, 'prefix': ''}}
{'sync_response': True}

arista@devbox:~$ pip install pygnmi==0.8.2

arista@devbox:~$ python t3.py 
ssl_target_name_override is applied, should be used for testing only!
Exception in thread Thread-5:
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/threading.py", line 973, in _bootstrap_inner
    self.run()
  File "/usr/local/lib/python3.9/threading.py", line 910, in run
    self._target(*self._args, **self._kwargs)
  File "/home/arista/.local/lib/python3.9/site-packages/pygnmi/client.py", line 940, in enqueue_updates
    for update in subscription:
  File "/home/arista/.local/lib/python3.9/site-packages/grpc/_channel.py", line 426, in __next__
    return self._next()
  File "/home/arista/.local/lib/python3.9/site-packages/grpc/_channel.py", line 826, in _next
    raise self
grpc._channel._MultiThreadedRendezvous: <_MultiThreadedRendezvous of RPC that terminated with:
        status = StatusCode.UNIMPLEMENTED
        details = "Extension not supported"
        debug_error_string = "{"created":"@1658653512.927644730","description":"Error received from peer ipv4:192.168.0.5:443","file":"src/core/lib/surface/call.cc","file_line":966,"grpc_message":"Extension not supported","grpc_status":12}"
>
^CTraceback (most recent call last):
  File "/home/arista/t3.py", line 22, in <module>
    for device in inventory:
  File "/home/arista/.local/lib/python3.9/site-packages/pygnmi/client.py", line 1004, in __next__
    result = self.next()
  File "/home/arista/.local/lib/python3.9/site-packages/pygnmi/client.py", line 1016, in next
    return self._next_update(timeout=None)
  File "/home/arista/.local/lib/python3.9/site-packages/pygnmi/client.py", line 1090, in _next_update
    return self._get_one_update(timeout=timeout)
  File "/home/arista/.local/lib/python3.9/site-packages/pygnmi/client.py", line 969, in _get_one_update
    return telemetryParser(self._updates.get(block=True, timeout=timeout))
  File "/usr/local/lib/python3.9/queue.py", line 171, in get
    self.not_empty.wait()
  File "/usr/local/lib/python3.9/threading.py", line 312, in wait
    waiter.acquire()
KeyboardInterrupt