How do I sort a map by order of insertion?

None of the standard library collections maintain insertion order. You can instead use IndexMap from the indexmap crate, which preserves insertion order as long as you don’t call remove.

use indexmap::indexmap;

let map = indexmap! {
    "Z" => 1,
    "T" => 2,
    "R" => 3,
    "P" => 4,
    "K" => 5,
    "W" => 6,
};
    
for (k, v) in map {
    println!("{}: {}", k, v);
}

// Z: 1
// T: 2
// R: 3
// P: 4
// K: 5
// W: 6

It accomplishes this by storing a hash table where the iteration order of the key-value pairs is independent of the hash values of the keys. This mean that lookups may be slower than the standard HashMap, but iteration and removal is very fast.