Carlos Garnacho of GNOME developed the protocol support for adding Drag and Drop actions to Wayland. This protocol addition is meant to make Wayland DnD support closer to what's offered in the X.Org world with the XDND protocol.
For dragging and dropping, the protocol additions can now notify the compositor of available actions to do on the data source and actions on the destination side along with any preferred action.
More details on this Wayland DnD actions support can be found via the documentation with this Git commit.
The DnD actions support is one of the features that was on the list for what needs to be done so Fedora can default to Wayland. This new protocol support will be found in the Wayland 1.10 release due out in mid-February.