PyO3 + Maturn is fine, but it's a bit tedious if you have a big API. Some annoyances:

  - Enums with inner types require hacks
  - No clean way to make your Rust enums into Python enums
  - More boilerplate than you should have. I think I will have to write my own macros/helpers to solve. For example, you need getters and setters for each field. And the gotcha: You can't just macro them due to a PyO3 restriction.
  - No way to use other Python-exposed rust libs as dependencies directly. You have to re-expose everything. So, if your rust B lib depends on rust A, you will make a PyO3 Rust A package, but instead of re-using that in PyO3 Rust B, you will copy+paste your PyO3 Rust A boilerplate into PyO3 Rust B.

If you're maintaining a single lib and want to expose it to Python, it's fine once you find a pattern that works. If you have a network and/or your API is large or not stable, it's a mess. (but doable)