Update on the search:
Ok, so apparently, the trouble was with the commands.py that is in C:\Python27\Lib
For some strange reason, when in maya, you type import commands, it doesn't import the commands form C:\Python27\Lib but from somewhere else. And this other commands doesn't have the attributes.
When making a dir on it :
['__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__']
So I juste copy/paste the commands.py from C:\Python27\Lib to C:\Python27\Lib\site-packages and C:\Python27\Lib\site-packages\future
and now in Maya when I try dir (commands) I get :
['__all__', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'getoutput', 'getstatus', 'getstatusoutput', 'mk2arg', 'mkarg']
And ftrack seems to works in maya 2020 python 2.7.17
I'll continue to look for a way to make it work with python 3.7