No, GP can just not use Rust, they don't have to use GC languages to have something that makes sense and doesn't force you to always have a debate with the compiler about even simple things.

If they used Odin (or Zig) they could've looped through that dynamic array no problem, in fact:

    package example
    
    import "core:fmt"
    
    main :: proc() {
        xs: [dynamic]int
        append(&xs, 1, 2)

        for x in xs {
            fmt.println(x)
        }
        
        fmt.println(len(xs))
    }

It is ridiculous that Rust complains even about the simple for loop and to say that this somehow comes down to "Well, everyone would do it this way if they cared about memory safety" is just not really true or valuable input, it sounds like what someone would say if their only systems programming experience came from Rust and they post-rationalized everything they've seen in Rust as being how you have to do it.

My tips to people who maybe feel like Rust seems a bit overwrought:

Look for something else, check out Odin or Zig, they've got tons of ways of dealing with memory that simply sidestep everything that Rust is about (because inherently Rust and everything that uses RAII has a broken model of how resources should be managed).

I learned Odin just by reading its Overview page (https://odin-lang.org/docs/overview/) and trying stuff out (nowadays there are also good videos about Odin on YouTube), then found myself productively writing code after a weekend. Now I create 3D engines using just Odin (and we in fact use only a subset of what is on that Overview page). Things can be simple, straight forward and more about the thing you're solving than the language you're using.