Unfortunately doesn't seem like many, as most apps use some sort of toolkit, and generally most support either only X11 or X11 and Wayland, supporting only Wayland isn't popular.
Though people who want to avoid using toolkits would probably do that, as Wayland's API is much more sane for apps.
However for example Waydroid only supports running on Wayland, and somehow nobody has created a reverse XWayland yet (People that ask for this get constantly redirected to nested compositors which is absolutely the wrong thing, a proper reverse XWayland would seemlessly integrate the apps like Xwayland does, and you could drag them, transparency would work, and https://wayland.app/protocols/xdg-shell#xdg_surface:request:... would be converted to _GTK_FRAME_EXTENTS, etc)