Make command line app behave like a normal macOS app? Is it possible to make a command line app  behave and act like a normal Cocoa app?

I want to be able to set command line app Zathura, for example, as a default pdf viewer.

I want it to appear in Alfred/Spotlight when I search for it, and if an instance is already running, typing "Zathura" and then Return would bring up that instance instead starting a new one.
There is an app called Platypus which will take shell scripts or python scripts and make them into an app that you can just double click to run. The app is free. I use it to convert python scrips but it also works for command line scripts.