If you haven’t yet, I highly recommend to check FastAPI for your python backend: https://fastapi.tiangolo.com/. OpenAPI is a core part of it, making it simple to integrate with other tools such as docs and clients generator
Or you can go straight to Starlette [0], which is much more streamlined to develop with. FastAPI is based on it itself, and while it provides many additional bells and whistles I find it messes things up significantly.
[0] https://www.starlette.io/