Help Creating Drop-down within the Hamburger Menu

Hi,

I’m just wondering if it’s possible to create headings with sub-categories that open and drop-down.

I’m using woocommerce with mega menus and better menus.
We have the effect we want on the desktop version of our site (https://imgur.com/i7ViuHl) but on mobile only the highest-level categories are shown. (https://imgur.com/a/pB6fm)
Clicking one of these brings you through to a page with all of the aforementioned subcategories, which is not ideal.

Is there a way to make it so that when you click one of these headings on mobile, it drops down to reveal the sub-headings we have on desktop?

Thanks for your time and let me know if you need clarification.

The page I need help with: [log in to see the link]