Self-Hosted ChatGPT Clone Platform

I want to run my own ChatGPT-style interface—similar to OpenWebUI—on hardware that I own. The backend model is already in place; what I need is the full application layer that lets people sign up, chat, and, when desired, execute small code snippets inside an isolated sandbox... (Budget: $250 - $750 AUD, Jobs: API Development, Artificial Intelligence, Backend Development, Chatbot, Docker, Frontend Development, JavaScript, Node.js, React.js, Web Development)