I integrated some basic CEF stuff (enough get to get a basic browser working) into a Rust codebase (https://github.com/hamaluik/cef-simple). It was a massive pain at first, but much easier once you give up on the safety and "idiomacy" of Rust and accept that you have to write in more of C/C++ style. For the parts that can't be written purely in Rust, it ends up being not really any more painful than writing it in C++ anyway.