

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.
While people in power are absolute evil most of the time, this is not an excuse to change your own morals for the worse.
Small acts of kindness, when taken in decent quantity, change the world no less than massive fraud and sex trafficking.
That said, one of the most moral things to do is to be on the lookout for powerful people doing nasty things and do everything in your capacity to prevent or at least retaliate. This makes abuse less common, and goes a long way to restore democracy and responsibility for everyone.