We currently have respective dunder methods for bool/ints/floats, so if just for consistency x.__complex__() seems nice. Personally I've found the other methods hella useful for array-api-tests and Hypothesis, so imagine this will prove useful too.

I think we'd want to specify this just for complex-valued floating-point arrays, and adopters can choose to support real-valud float arrays if-and-however they so wish.