Just a bit more info on this – when I change the front page or the home page template to “default template” from “portfolio page template”, it shows the sharing buttons. However, it doesn’t the portfolio page template is set.
Sorry been quite busy with life in general so have just had the chance to test out what you advised. This worked really well for some of the other stuff I was looking to remove from mobile view such as the Featured Content from the sketch theme. But I’m struggling to find the class that references the tiled gallery. Not sure which class to use and therefore haven’t been able to set the gallery to ‘thumbnail’ if accessed on a mobile.