I am using phone for now, works okay but perhaps smaller font/logos for main subjects?
Just to add up to this subject - I like how it looks on desktop, I think mobile version should be similar. No need for subcategories on mobile, makes it look a bit wonky IMO.
Being an old luddite I don’t use a lot of phone apps but layout seems OK as it is and font size looks good, even without my reading glasses. 
Interesting request, we’ll need to see if that is possible out of the box and test with it.
Custom tweaking/coding will require more assessment, especially if new release owuld roll it right back.
If you have Android app try switching between desktop and mobile view and have a look at the main page, see if you share my opinion and if big icons alone don’t look better 