And the latency depends on the compositor. I believe Arcan achieved 0 frame compositor latency with Wayland. I think the latest gnome-shell Mutter is there as well.

If your application can draw its frame and get its notification into the compositor before the compositor begins to draw, there's no need for any additional delays.

If your app cannot complete a draw in the time left in the frame by the compositor, then it'll be one frame behind.