Sorry for the late response on this. I tried to respond earlier but was stymied by issues with the mailing list server.
The last time this was discussed I was the one to raise the suggestion. You can find the start of the thread:
25 Aug 2016: SI scale factors in Python https://firstname.lastname@example.org/message/HVHRIR...
The gist of the suggestion was that SI scale factors have been an internationally standardized way of writing real numbers for over 50 years and is a much nicer than using exponential notation, so wouldn't be a good idea to add support for SI scale factors directly into the language. There was considerable discussion but no consensus emerged for changing the base language.
However, the discussion bore fruit in QuantiPhy (https://quantiphy.readthedocs.io), a Python package that incorporates the ideas and suggestions that came up during that discussion. So, while it is still not possible to use SI scale factors in Python real literals, you can use this package to easily use SI scale factors in IO.