> Since you could just design your `?` to encourage wrapping instead.

Which is exactly what Rust does -- if the error returned by the function does not match the error type of `?` expression, but the error can be converted using the `From` trait, then the conversion is automatically performed. You can write out the conversion implementation manually, or derive it with a crate like thiserror:

    #[derive(Error)]
    enum MyError {
        #[error("Failed to read file")
        IoError(#[from] std::io::Error)
        // ...
    }

    fn foo() -> Result<(), MyError> {
        let data = std::fs::read("/some/file")?;
        // ...
    }

You can also use helper methods on Result (like `map_err`) for inserting explicit conversions between error types:

    fn foo() -> Result<(), MyError> {
        let data = std::fs::read("/some/file").map_err(MyError::IoError)?;
        // ...
    }