Filtering without Search & Discovery app

[gaborify]

Hi, I am learning Shopify theme development and I'd like to understand how filtering works.

Does filtering work without the Search & Discovery app? 

I am using the Dawn theme, and I am trying to print the filters available in main-collection-product-grid.liquid:

  <ul>
    {% for filter in collection.filters %}
      <li>{{ filter.label }}</li>
    {% endfor %}
  </ul>

...but all I get is "Availability" and "Price", even though I have products with various Vendors, Product Types and Metafields set up in Shopify Admin.

My understanding is that the collection.filters array should be populated by the Shopify backend, runtime, based on the properties of the products of the given collection. In my case, various product vendors and types should show up, but they don't.

I find the official documentation confusing. Some pages imply that Storefront filtering should work out-of-the-box, other pages imply that you need Search and Discovery app.

Shopify Sidekick gave me an answer I found nowhere online, so I'm guessing it's wrong. "Without the Shopify Search & Discovery app, only the default filters (availability and price) are available in your theme using the collection.filters Liquid object."

What am I missing? Thanks in advance!