What makes Linux appealing to me is the extent of customizability, but I didn’t find many answers when looking up with desktop environment is them most customizable. Some say KDE is most customizable than say, Gnome, but doesn’t Gnome support CSS customization while KDE doesn’t?
Subjective. If you’re talking about functionality, then GNOME wins. If you’re talking about UI, then KDE might have the upper hand.
If you want to fundamentally change the way something operates, then it’s neither of those.
If you don’t mind me asking, what makes gnome more adaptable in terms of functionality than KDE?
Gnome makes it easier to make you adapt imo. KDE gives you so much options that it’s scary and overwhelming to learn and configure when you just want to use something in the way it’s intended to be used immediately.
Gnome is very functional, it’s just meant to function one very specific way.
And please don’t theme it.