I'm not talking about a library, I'm more concerned with DEs implementing the library.
Things like swipe with three fingers to switch desktops, swipe up with three fingers to show open windows etc. Why is all that stuff tied to a UI theme?
Swipe to switch desktops is implemented in GNOME Shell and Mutter. GNOME Shell's default CSS style is also called Adwaita, but it in no way affects the availability of gestures.
If you just don't want the ui design pattern just use the gesture, it's already there waiting for you to make something with it.