"Go To Declaration" goes to definition/implementation instead

I think the current behaviour is correct.
The import is not the method declaration after all (and you could use the method without importing it, like module.method()).

However, yes, a way to navigate to the import would be welcome.

The import in Python is the function/class declaration – there's no other way to make function/class available in given module (short of implementing it in this very same module). Using module.method() doesn't change this – you can think of this as implicit method declaration.

Generally terminology used in "Navigate" menu is misleading. "Implementation(s)" is concerned with implementation(s) of subclasses whereas I bet most people think of it as "implementation of the thing I'm currently looking at" when they see it.

I suggest that:
"Declaration" goes to import (one can argue it should also be renamed to "Import" then).
"Implementation" goes to implementation of given function/class.
"Subclass(es)" goes to implementation of subclass thus it's the same as current "Implementation(s)".

I have a feeling that entries in "Navigate" menu come from IDEA's support for Java and there was not too much thought in how they should look like in Python.