How would the dynamism and expressivity of something like Django port to Nim? I love the whole declarative paradigm of the Django forms and models API. Is Nim good at this kind of DSL-ish plasticity?
Extremely well I'd say. Nim has a very powerful macro system, and DSLs are very common across various modules. Haven't used Django myself, but something like Jester (https://github.com/dom96/jester) or Karax (https://github.com/pragmagic/karax) is a good place to start if you want to do web development in Nim.
i'd say so: i think many rails/django concepts are translate-able to metaprogramming in nim, not always with the same idioms, but usually there is a way to do it, and you can typecheck some things