Hi there! I'm interested in your project. I have experiences in making GUIs either using tkinter, pyqt or webapps that could be either run on your local computer or a vps. I'd suggest you the latter (web app in django or flask which are python projects), some of the reasons are the following:
* In a Django app for example the code will have a better structure, this is somewhat tricky in tkinter or pyqt so this adds a plus when you think about the maintainability of your code/project. (If you decide to follow a tkinter/pyqt/kivy option then demand to the 'backends' to be programmed in classes and in separate scripts, just a suggestion)
* A web project will have many built-ins middlewares to interact with databases, files, security and so on.
* Because of the first reason the project will be easier to read for a future freelancer or even for the same one, this means that given that the web app forces you to follow certain patterns then you'll know where to find what you're looking for.
* You'll be able to run your app from your computer, phone, etc. And it'll be less riskier for cross-platform compatiblity.
Well... these are some of the reasons, there are always pros and cons for each one of them. As a final suggestion, ask to your selected freelancer to document all of the scripts, functions, classes, etc following some of the conventions around there.
Good luck in your project!