If nobody has any other suggestions, try Phind.com with GPT4 selected in the drop-down. You get 10 free tries a day, the downside is that they use your data for training their in-house model. That's as good as you're gonna get for less known languages, for free.
Since all local models suck for Rust, I'm gonna assume all general purpose coding models suck for anything but the most common languages (Python, JS/Type Script, C/C++, Java). Although there is an/a SQL only model that is really good with SQL. Maybe someone did one for PS...