How Hard is It to Develop a Web or Mobile App for My Chess Algorithm?

I'm looking to create an app for a chess algorithm I have in mind. While I'm fairly comfortable with Python and currently learning C#, I've been told that developing an app can be quite challenging. I want to know how much extra effort it would take to turn my program into a functioning app. Are there any alternatives to app development that would allow me to present my code in a more user-friendly way? I'm determined to do most of the coding myself, although I'm open to using existing applications to simplify the process if needed. Essentially, I want the app to allow user inputs, possibly via buttons or a drag-and-drop interface, and generate outputs based on my program. Any advice would be appreciated!