A user running the Dawn theme wants to add thumbnail images for collections in their header menu dropdown, similar to mega menu implementations on other sites. They’ve shared screenshots of their store and an example reference.
Proposed Solutions:
Custom code approach: A developer confirmed this is achievable through custom Liquid code modifications, as Dawn’s default mega menu only supports text-based navigation. The developer offered assistance with implementing the necessary code changes.
App-based solution: Another contributor recommended Meteor Mega Menu, a Shopify app specifically designed for adding image-based navigation to mega menus. They suggested checking the app’s demo store (Prism menu) as a reference.
The discussion remains open with the original poster yet to indicate their preferred approach or implementation method.
Hello 
Adding easy-to-navigate images to a mega menu is exactly why we created Meteor Mega Menu. If you’re open to an app, I think it would be purrfect for your site 
Check out the Prism menu in our demo store, it should be really close to what you are looking for right out of the box.
I hope this helps.