You might remember there is an amazing project Tectonic, aiming as a modern alternative/rewrite of TeX/LaTeX engine, exposed as a Rust crate. It was announced at this board before. But the core of it still uses C code. Someone stepped in and started a conversion to Rust using c2rust automated conversion tool. If anyone wants to help - you can always join the efforts and send a pull request to the corresponding repository. There is a list of issues that would welcome your help.
Just an update - seems there is a significant progress in the passed 10 days: https://github.com/crlf0710/tectonic/commits/oxidize
Some major tasks would benefit from the external help: