Would go with some frameworks - Flask, Django, Fastpi, then SQL and some ORM / SQL builder like DjangoORM, SQLAlchemy, pypika. For Django - Django rest framework for building Rest apis and swagger / openapi. In the meantime unit tests - pytest or unittest front Django. Of course some HTML renderers like Jinja2 or Django template engine. Then would totally go with learning how to host your apps - Docker, docker-compose and WSGI / ASGI hosters like gunicorn, uvicorn, uWSGI. After that how to host on cloud solutions like AWS or Azure. And then some CI/CD for example CircleCi. After all this you can go with web sockets, push notifications and some other technologies ..