Ask HN: Best Tech Stack for a Chat App with AI: Python vs. Nest.js for Back End?

I am working on a B2C startup and need to design the backend for a website and mobile apps supporting a chat application. The platform will incorporate AI/ML models to analyze chats and user inputs, alongside a notification system for users. My initial idea is to separate the backend and AI services. Should I use Python for both the backend and AI components, or would it be better to leverage Nest.js for the backend, while using Python for AI?