My problem is that I can't access the $cat_slug variable inside the [display-posts] short-code. The idea is to use that variable to dynamically pick post categories via the array returned from get_the_category(); I thought it was a scoping issue but there's no function present. Do for loops have a scope that I'm not aware of? Any help is greatly appreciated as I'm fairly new to php! <3

Here's the snippet I'm working with; I've left in my sudo code to illustrate my thought process.

    //gets an array of objects containing post meta data
    $term_meta = get_the_category();

    //define global variables
    $cat_slug = 'test';

        //if array of objects is not empty,
        if ( ! empty( $term_meta ) ) {

            //for object in array with an index of $x...    
            for($x = 0; $x <= count($term_meta); $x++){

                //set $wp_term_object to the object in the array with an index of $x 
                $wp_term_object = $term_meta[$x];

                //set $slug to the value of key 'slug' in object $x 
                $slug = $wp_term_object->slug;

                    //if $slug doesn't equal 'featured...
                    if($slug != 'featured'){

                        //set $cat_slug equal to $slug 
                        $cat_slug = $slug;
                    }
            }
        }
echo do_shortcode('[display-posts category="'. $cat_slug .', featured" posts_per_page="1"]');