>If you build it as a CLI, you can get the GUI for free via Gooey But then you've just added a dependency and, unless you vendor that thing, or don't update it

>If you build it as a CLI, you can get the GUI for free via Gooey But then you've just added a dependency and, unless you vendor that thing, or don't update it in the future, you've no way to ensure it doesn't screw up your application at some point down the road. Design the API, write the code, then have your front end(s) (cli, GUI, etc) call into it. Best of all worlds, no additional dependency.