I am new to C++ modules. Let’s say I am creating dll , and I don’t want my users to see implementation details of my class . How can I achieve this in C++ modules ? Mostly I am seeing examples over internet , implementing functions in the same file . Can I safely say , module interfaces are similar to header files & module implementation is similar to cpp file ?
Here is my example implementation , is this correct ? I am using visual studio 2022.

//AnimalParent.ixx file

export module Animal:Parent;

export class Animal
{
public:
    virtual void say();
};

//AnimalParent.cpp file

module Animal:Parent;

#include <iostream>

void Animal::say()
{
    std::cout << "I am Animal" << std::endl;
}

//Animal.cat.ixx file

export module Animal:Cat;

import :Parent;

export class Cat :public Animal
{
public:
    void say() override;
};

//AnimalCat.cpp file

module Animal:Cat;

#include <iostream>

void Cat::say()
{
    std::cout << "I am cat" << std::endl;
}

//Animal.ixx file 

export module Animal;

export import :Parent;
export import :Cat;

questions :

1. Is this implementation correct ?
2. can I safely assume , files contain export module name(.ixx extension)– similar to header files & module name – similar to respective source file ?
3. If I shift this dll to my customer , what all should I give ? my dll and the folder contains .ixx files?
4. And how they will integrate my dll . in current header files system , they will refer to header files directory to Additional include directories , and link the lib. Here do they have to refer the folder contains .ixx files in Additional include directories & link the lib.