Can a NavMenu be responsive in element-ui?
The Element, it is not designed for a mobile platform, it is for a backstage management system. I'm not sure whether the team has a plan for supporting responsive design or not. On the other hand, the Element team provides a responsive grid system to make a flexible layout.
If you consider building a responsive navigation menu, then you have to implement it for yourself to achieve your cases.
Just to make people's life a little more convenient, I've created a simple responsive menu template using Element a couple of days ago.
Hope this helps you, to get some ideas.