You don’t really need to add the whole UnityEngine namespace. That will only bloat the menus 🙂
Just add the types you need in the Preferred Types Editor. Search for “Cursor” and add Cursor and CursorLockMode types.
Then the code you want to achieve, can be created with a custom function like this:
(The “Not Equal” node by the way, can be found in “Functions/Implemented/Logic Operators\Any” category).
If you have any questions, or need any further clarification, please let me know.