Creating a complete C++20 serialization library in the style of Karandara is a complex and time-consuming task, so I can provide you with a simplified example to get you started. The following code demonstrates a basic C++20 serialization library that can serialize and deserialize objects using the C++20 standard library features. This example uses a similar style to Karandara's approach but is simplified for demonstration purposes.

```cpp
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <sstream>
#include <type_traits>

namespace serialization {

    // Serialization trait to check if an object can be serialized
    template <typename T>
    struct is_serializable : std::false_type {};

    // Serialize objects to a stream
    template <typename T>
    void serialize(std::ostream& os, const T& obj) {
        static_assert(is_serializable<T>::value, "Object is not serializable");
        os << obj;
    }

    // Deserialize objects from a stream
    template <typename T>
    void deserialize(std::istream& is, T& obj) {
        static_assert(is_serializable<T>::value, "Object is not deserializable");
        is >> obj;
    }

    // Serialize vector
    template <typename T>
    void serialize(std::ostream& os, const std::vector<T>& vec) {
        serialize(os, vec.size());
        for (const auto& item : vec) {
            serialize(os, item);
        }
    }

    // Deserialize vector
    template <typename T>
    void deserialize(std::istream& is, std::vector<T>& vec) {
        size_t size;
        deserialize(is, size);
        vec.clear();
        vec.reserve(size);
        for (size_t i = 0; i < size; ++i) {
            T item;
            deserialize(is, item);
            vec.push_back(item);
        }
    }

    // Specialization for std::string
    template <>
    struct is_serializable<std::string> : std::true_type {};

    // Specialization for custom user-defined types
    struct Employee {
        std::string name;
        int age;

        // Define serialization functions
        friend std::ostream& operator<<(std::ostream& os, const Employee& obj) {
            serialize(os, obj.name);
            serialize(os, obj.age);
            return os;
        }

        friend std::istream& operator>>(std::istream& is, Employee& obj) {
            deserialize(is, obj.name);
            deserialize(is, obj.age);
            return is;
        }
    };

    // Specialization for the Employee type
    template <>
    struct is_serializable<Employee> : std::true_type {};

}  // namespace serialization

int main() {
    using namespace serialization;

    // Serialize an object
    std::ofstream out("data.txt");
    Employee employee = {"John", 30};
    serialize(out, employee);
    out.close();

    // Deserialize an object
    std::ifstream in("data.txt");
    Employee loadedEmployee;
    deserialize(in, loadedEmployee);
    in.close();

    // Display the loaded object
    std::cout << "Loaded Employee: " << loadedEmployee.name << ", " << loadedEmployee.age << std::endl;

    return 0;
}
```

In this simplified example:

- We have a `serialization` namespace that provides `serialize` and `deserialize` functions.
- It uses static assertions and specialization to determine if an object can be serialized or deserialized.
- It includes a custom serialization implementation for the `Employee` struct.

This code provides a basic framework for serialization and deserialization of objects. In a production library, you would need to handle more complex scenarios and potentially support polymorphism, versioning, and error handling, among other features.