First of all - hello python-ideas. I liked the look of the archives, so I thought I'd chip in, if it's OK.

And what about:

<f locals>.g
and
<<xyzzy locals>.f locals>.g

In the end I like the non-nested version better.

xyzzy.<local f>.<local g>

or, preferably,

xyzzy.<instance.f>.<instance.g>

It's non-nested, shows the locality and maps the locality to the variable.

If not showing function instances is disliked, maybe drop the period between the function and "<locals>" from yours:

xyzzy<locals>.f<locals>.g

or, again,

xyzzy<instance>.f<instance>.g

I think this is just cleaner than:

xyzzy.<locals>.f.<locals>.g

because it doesn't imply that xyzzy has a single set of locals - especially using <instance>.