Sorry for the click-bait-y title (especially the “in 2022” part), but I searched fruitlessly for way too long and found too many woefully outdated answers to this. Ultimately what I found still wasn’t quite the complete answer, so I modified it a bit myself to arrive at the following.

The goal here is, as the title suggests, to get the WooCommerce main shop page to only show your featured products. Why this isn’t just a checkbox option in WooCommerce is beyond me. But then a lot of the decisions made by the WooCommerce dev team are beyond me. (Excuse me, Professor Brainiac, but I’ve built e-commerce platforms from scratch and, uh, I think I know how a proton accelerator… oh wait, never mind.)

Anyway, this is it:

add_action('woocommerce_product_query', function($query) {
    if (is_shop()) {
        $query->set('tax_query', array(array(
            'taxonomy' => 'product_visibility',
            'field' => 'name',
            'terms' => 'featured',
            'operator' => 'IN',
        )));
    }
});

What exactly is happening here? Well, as noted by the most helpful resource I found, since WooCommerce 3 (currently on 6.1.1), the “featured” status has been handled by the product_visibility taxonomy, and not by the _featured post meta field. So this needs a tax_query and not a meta_query.

Beyond that, we’re making an extra check that we’re on the shop main page — so this doesn’t affect category archive pages. And we’re using the woocommerce_product_query hook, not pre_get_posts as some other examples suggest, so it only runs on WooCommerce queries and we can skip adding extra conditionals for pre_get_posts to run on, you know, every single post query on every page of the site, including admin.

That’s all there is to it. Now your main WooCommerce shop page will only display featured products, and nothing else changes.