If a web app would work, you can use your Python skills to build it quickly with Anvil. They handle hosting and deployment, with built-in database and user authentication. There's a drag-and-drop UI designer. But we're not talking a "no code" solution here. You write all the logic (both server- and client-side) in Python.
I'm not sure I fully understand what you're looking to do, but Anvil would allow you to quickly build a GUI as a web app written all in Python (with built-in user authentication that likely integrates seamlessly with your existing user accounts[1]). A common use of it is to pull together pre-existing services. Their Uplink functionality allows you to seamlessly connect with your Python backend: https://anvil.works/docs/uplink/quickstart
Consider building the app using Anvil. Both front- and back-end are written in Python, with Stripe payments support built-in. Anvil speeds up the prototyping process considerably. But it's also a platform that can scale up, with clean architecture making maintenance easier. A unique advantage is that, if you know some basic Python, you will be able to understand how the app works yourself and make changes to it directly. A simple e-commerce template can be seen here: https://anvil.works/learn/examples/shop-template-guide The downside is that not many developers know Anvil yet, so it may be difficult to hire for it. The main place to recruit an experienced Anvil developer is here: https://anvil.works/forum/c/job-adverts/ (Alternatively, most any developer would be able to pick it up quickly if you ask them to.)
