The entire backend in Rust, using actix-web framework and async libraries for postgres and redis. You're not going to rapidly prototype anything with Rust for

The entire backend in Rust, using actix-web framework and async libraries for postgres and redis. You're not going to rapidly prototype anything with Rust for your first 12 months working with the language, depending on your motivation and your ability to write missing parts for security middleware. However, once you've gone through that, you can be just as productive with an async Rust stack as you can with a Python one. Your prototype will also be ready for the "no time to refactor" mandate that makes it your production system. Actix-web framework and async libraries for postgres, redis, and rabbitmq are all mature and well-documented. I realize you said quick prototype/MVP, but all of this comes at little additional cost once you know how to adopt and integrate quickly.