How to make a separate timezone for each browser on selenium?

Question

Python

I am using firefox-based browser with selenium to python in multiple threads. And I need each individual browser window to have its own timezone. Normal firefox takes the timezone when it starts from the system and saves it, that is, if the timezone changes when firefox is launched, then it will not change in the browser itself without restarting. But in my browser everything is different, it always takes the timezone from the system. Can I somehow set a separate time zone for each window? Perhaps somehow through JavaScript. I tried the RunAsDate software, but without success. I will be grateful for the answer.
The browser I use is https://vektort13.pro/#progs

Answer 1

On os x this is enough

import os, time
os.environ['TZ'] = 'US/Eastern'
time.tzset()

result checked on https://whatismytimezone.com