I have objections and worries - but this is the greatest change in the horizon in the living threads around. 
So, I’d like to see updates if any.
As far as I am concerned, I keep my last idea floating: not trying to eagerly recursively freeze everything under the Sun, but rather, at least in Python code, replace everything retrieved from an eagerly shallow-frozen object with a proxy, which will present a lazily frozen behavior.
So, one won’t need to freeze sys.set_int_max_str_digits, if one has a method in a frozen object checking sys.version