That depends a lot on how you define “correct C”.
It is harder to write rust code than C code that the compiler will accept. It is IMHO easier to write rust code than to write correct C code, in the sense it only uses well defined constructs defined in the C standard.
The difference is that the rust compiler is much stricter, so you need to know a lot about details in the memory model, etc. to get your code past the compiler. In C you need the same knowledge to debug the program later.
I’d go for open source projects. They usually have bigger code bases and good practices, that they enforce on their contributors with code reviews and such.
It’s a good way to get feedback on your code, something miss out on personal projects and get much less of in university and corporate projects.