Maybe you can add an option for the users to communicate with their local LLM as I mentioned before? For example I have an Ollama with a gemma model. I can use the website to scrap texts from the forum, then throw them to my LLM to check, and show the result on the website in real time. I know gemma isn't the best model for testing AI texts, but this is just an example. This means users don't have to download the model manually and have more control over which models they wanted to use.
I will look into your suggestion. If I am able to implement what you are suggesting, then I will give it as another option to the user. BTW.. if you are using Chrome, you can paste any text into the integrated Gemini AI to check whether an AI has written it. It will give you factual information, but it will not be able to give the percentage of text being written by the AI.