Best way to have a mega menu at the moment
I found https://joomlaprox.com/product/maxi-menu-ck-uikit-override-theme in the internet, but it didn't worked for me, because I am using the UIkit-Template with Yootheme Pro. I tried to get it working with the support help of JoomlaproX but they had no time being bussy with other things and I waited about a week for a solution, which didn't come finally.
So I tried to design my own maxi menu ck (https://www.joomlack.fr/en/joomla-extensions/maximenu-ck) originally with the possibilities of this great component. It was a little bit of work, but finally I had exactly the same menu design as originally in the yootheme template and now I can change the columns and all design details on the fly.
So you could take this way. It is a one day work, but at the end you have a very good result.