EST was ambiguous in the past [1]. But now the pytz code from the answer
returns a single utc offset and many timezones that use EST
abbreviation.
Look, even though Einstein's theory of relativity tells us that time and space are the same, PEP 495 is only trying to disambiguate times, not places. You will not be able to use the fold value to differentiate between Moscow and Nizhny Novgorod. Any support for that will have to be covered in another PEP.