In the Mobile Layout report editor you can reposition or not use visualizations from regular layout. But that’s all you can do… you cannot customize the format of your visualization.
Start with a report like this and select Mobile Layout:
This will open the mobile layout editor:
You can now choose which visuals to add:
Adding the Responsive Slicer
The current slicer is not responsive. To change this, select Format and then change the orientation from Vertical to Horizontal.
The slicer should now look like this:
You can now toggle responsiveness on and off.
With responsiveness on, now add the slicer to the mobile view: