people talk a lot about MyPy but I must recommend Pyright as a better alternative. It's much more robust.

In my experience the main problem with MyPy is that when it's unsure about what's going on (especially due to imports it doesn't understand, sometimes because of misconfiguration) it just gives up on type checking with absolutely no warning. Pyright does not have this failure mode and handles Unknown types properly (with configurable strictness)