Thanks a lot for your work! We recently switched to FastAPI from Django rest framework at Etebase[1] and it's been an absolute pleasure!
P.S, if anyone is interested, it took a bit of hacking, but we managed to get two unusual things working:
1. Use MsgPack instead of JSON. It works great and wasn't too much of an effort (the existing libraries are done wrong and don't work well).
2. Use the Django ORM with FastAPI. This was quite hard to do and quite manual as the Django ORM assumes the rest of the Django stack is in use.
Etebase is open source[2], so you can just check out how it's done if you are interested. I'm also happy to help if anyone has questions.
I really hope we get a good async ORM soon. I'm currently using SQLAlchemy 1.4b1 in a side project, though the typing (and mypy plugin) are unfortunately not there.