I’d say go KDE.

GNOME looks like it will be good for portable devices, but it’s kinda not.

First, in my experience, Fedora on GNOME completely ignores battery limits (which are also set by jumping through so many hoops you can’t even imagine). It just drains this thing to 0, which is not great for longevity. KDE, on its end, has it all in the GUI and it works flawlessly on all distros I tested.

Second, KDE has made plenty of great optimizations for touchscreens. A while ago, it was not great, but now it’s just the best at handling them, especially if you theme it respectively and do not rely on defaults.

Third, customizations are so much better in KDE. You can make her laptop look and feel like a MacBook in no time, and edit everything to be touch-friendly.

One thing GNOME does well though for the use case you describe, though, is app theming, namely Adwaita. Luckily, Adwaita-themed apps and style editors for the rest are freely available on KDE, and you can even change their look as you like.

So, yeah, go KDE.

Alright, you bought me with this Amazing presentation and nice that you have a demo!