sairamuppugundla - If you format your question to use syntax highlighting, it will be more readable.
TL;DR: I use f-Strings where I can
First of all python2 is end of life, so when possible use python3
If you have an option, use latest python version.
As you have already mentioned, f-strings are supported in python 3.6 onward. But PyPI package f2format allows you to use it with python 3.3 onward.
Finally this might answer your question more directly (and better than I did)