You've got a lot of assumptions in there.
I think most desktops that are based on a Wayland compositor (e.g. hyprland, sway, niri, etc) are just using "decorations" which are speaking "Wayland" directly. Same for the terminal and other base apps. That's certainly the case for me.
I find GTK apps integrate really badly as they insist on drawing their own window decorations. I try to stay away from them if I can, and will prefer anything else.