Has P/Invoke been cross-platform for a decade? Additionally, does it parse C headers to create native type wrappers automatically? Last I checked (a long time ago), P/Invoke required you to annotate manually written prototypes?
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.