Ok, and the last part of the dark preference has landed - a uniform compositor-side crossfade like in macOS, iOS or (WIP) elementary OS. Now I'm happy.
Note: this may look laggy, but this is a recording of a VM. It's much smoother when it's not being recorded. Ditto the tearing.
@exalm ok great ! thanks
@Carnet yes, by now all core apps are handled. Nautilus almost missed it though - it merged the GTK4/libadwaita port pretty early on, but it has become clear that it won't be ready in time and it reverted like 2 days ago. But it has implemented dark support separately, so it will work fine.