...but hopefully not the last. People are playing (with BDFL's blessing) with the idea of types having just (qual)name as str.

By "first stdlib case" you mean "first builtin case", right? fractions.Fraction and decimal.Decimal are in stdlib. :-)

Yes, not all classes can (nor should) support the strong "literal_eval being left-inverse of repr" invariant, but IMO builtin value-like (having a meaningful ==/hash infrastructure separate from identity) classes should. Numbers are surely in that camp.