It seems the port is currently completely broken. I installed it using "pkg install pgxnclient". 

System: FreeBSD 13.1.

This is the output I am getting when launching pgxnclient (no matter if and what arguments I give it):

Traceback (most recent call last):
  File "/usr/local/bin/pgxnclient", line 33, in <module>
    sys.exit(load_entry_point('pgxnclient==1.3.2', 'console_scripts', 'pgxnclient')())
  File "/usr/local/bin/pgxnclient", line 25, in importlib_load_entry_point
    return next(matches).load()
  File "/usr/local/lib/python3.9/importlib/metadata.py", line 86, in load
    module = import_module(match.group('module'))
  File "/usr/local/lib/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 972, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/usr/local/lib/python3.9/site-packages/pgxnclient/__init__.py", line 11, in <module>
    from pgxnclient.spec import Spec
  File "/usr/local/lib/python3.9/site-packages/pgxnclient/spec.py", line 12, in <module>
    from six.moves.urllib.parse import unquote_plus
ModuleNotFoundError: No module named 'six'