https://ollama.ai/, this is what I've been using for over a year now, new models come out regularly and you just "ollama pull " and then it's available to run locally. Then you can use docker to run https://www.openwebui.com/ locally, giving it a ChatGPT-style interface (but even better and more configurable and you can run prompts against any number of models you select at once.)
All free and available to everyone.