My interest in Rust stems from a very good Python interop. There's a very small handful of compiled languages with that property: Rust, C++, Nim (which is itself quite niche)... That's basically it as far as I know. Swift doesn't seem to tick that box.
I would happily have something 50-100% slower than C++/Rust with good interop, alas there seems to be very little / nothing. Cython for various reasons isn't ideal.