How can I list only custom shortcodes?

The linked question shows you how to get all the shortcode tags in an array. So narrowing them down to specific ones is purely a PHP question. But the answer’s simple enough.

Use array_filter() on the array of tags with a callback function that uses strpos() to see if each tag contains the work you’re looking for. Since the shortcode tag is the key in the array, use ARRAY_FILTER_USE_KEY to use the actual shortcode tag for the comparison in the callback function:

global $shortcode_tags;

$shortcodes = array_filter(
    $shortcode_tags,
    function( $shortcode_tag ) {
        return strpos( $shortcode_tag, 'woocommerce' ) !== false;
    },
    ARRAY_FILTER_USE_KEY
);

In that example $shortcodes will now be all the shortcodes from global $shortcode_tags; that contain the word “woocommerce”.