Yes, P/Invoke has been working cross-platform for a decade with Mono. Have you heard of this thing called Gtk#?
P/Invoke does not parse C headers, but neither does this proposal.
P/Invoke does not parse C headers, but neither does this proposal.
This proposal will pave the way for jextract, though. I would argue this series of JEPs is much closer in spirit to something like Rust's cxx than P/Invoke is.