Advent of code provides a good chance for me to learn the Rust language. This blogger used it to learn the basic syntax and get to know the core and useful libraries in Rust, and I follow their suit. The year I used was 2022.
An example Rust Github repo of the same advent, from timvisee, is helpful for reference purposes. It also provides some basic boilerplates regarding how to arrange the Rust projects and from which I can learn the language.