Disclaimer: I am the author of this article.

Not really the same thing from what I can tell. Nitpicker is merely about isolating processes from each other, making sure keyboard input is only received by the currently focused process. Windows already does that, and so does Wayland in my understanding.

The goal here seems to be rather stopping applications with sufficient privileges to install a system-wide keylogger. Which Nitpicker likely solves implicitly – by providing an OS that isn’t exactly flexible in what it can do, meaning that security was bought by sacrificing usability.