There is also cxx.rs, which is quite nice, albeit you have to struggle sending `std` types back and forth a bit
Firefox solves this partly by not using `std` types.
For example, https://github.com/mozilla/thin-vec exists in large part because it's compatible with Firefox's existing C++ Vec/Array implementation (with the bonus that it's only 8 bytes on the stack compared to 24 for the std Vec).