Too much DOM for Mobile

Hi, we are using Mega Menu on few websites and now after Google new updates for Core Web Vitals, it shows we have a lot of DOM on website and its because of heavy header menu we have on websites.

On mobile, most of the Custom HTML is hidden but the html content is being loaded in website and on mobile, we do not want the html content.

Please let me know if we can use any function or make new extended class of Walker_Nav_Menu and modify start_el.

Waiting for response.