How to track a nested attribute in a Glimmer component?

I am building my first Glimmmer component in Ember and I had something like this in my template:

<p>Some val: </p>

I then made a corresponding .js component file and thought I would try to remove the long path from the HTML.

My first attempt was to make a getter:

get val() {
  return this.my_obj.some.deeply.nested.path.to.val;
}

With the template now:

<p>Some val: </p>

That works initially and displays the starting value assigned to the val variable, but it does not update when the underlying val changes.

So I thought I would try marking the getter as tracked, but that made the output disapear:

@tracked val;

get val() {
  return this.my_obj.some.deeply.nested.path.to.val;
}

I then tried this, but it's not valid syntax:

@tracked this.my_obj.some.deeply.nested.path.to.val;

So how should this be handled in a Glimmer component?

Surely the solution is not for the HTML to reference a deep path like this everytime the variable is referenced, however the new Ember docs, nice as they are, leave me none the wiser on this relatively simple/common case.