Qt 5 supports Wayland via the QtWayland plugin.
GTK 3 and later supports Wayland.
Experimental Wayland support was added in SDL 2.0.2, disabled by default.
The EFL port to Wayland is experimental - Ecore, Evas and Elementary have backends that target Wayland for both SHM and EGL based presentation. Full details can be found in the EFL website