There are various aspects of Python's local variable semantics that seem to harken to days when stack frames were implemented with dictionaries (eg: del). There may be a way to map this cleanly to register variables but it's not clear to me how you'd do this.

Beyond that there are several places where you can introspect the activation. See: locals(), some of the fields in the code object, etc. Again, there may be implementation techniques you can use to get around this, but there isn't an obvious and clean mapping to SSA values as there is for Lisp-like languages.