If he's not looking to change the layout or aesthetic, maybe a Razer BlackWidow v4 or a Logitech G815 or Corsair K100. Or he could go cheaper and move the macro keys to the very top with a Redragon K580, though I'd buy from someplace with easy returns for them.

I gotta admit though, gamer stuff that adds extra greeblies and ugly little microswitch buttons are not my jam. On the other hand a basic floating switches low profile "case" gets too much hate. Not everything needs to be a giant slab of machined aluminum. Ultimately, a column of macro-keys on the left is just not super common in the hobbyist space (though there are options, as you know), even less so when a board is already 100% width, though you could go full-bonkers and recommend him a buckling spring monster.