Is there a way to do a specific declaration of a template member function of a template class?

Question

I am trying to specify a template member function of a template class out of the class' context. Is it possible? (I understand that it is possible within the class context but I'd like to separate from the class' body)

template<typename T1>
class A
{
public:
    template<typename T2>
    constexpr bool test(T2 _)
    {
               return false; // imagine this is Unimplemented exception
    }
};

template<typename T1>
template<>
constexpr bool A<T1>::test<char>(char _) // <- this is not compiling
{
    return true; // imagine this is custom behavior for A<T1>::test<char>
}

int main() {
    A<int> test_var;
    static_assert(test_var.test<char>('a'), "Not working");
    static_assert(test_var.test<int>(5) == false, "Not working");
    return 0;
}

The compilation error from x86-64 gcc 12.2 -std=c++20 -O2 is:

<source>:13:10: error: invalid explicit specialization before '>' token
   13 | template<>
      |          ^
<source>:13:10: error: enclosing class templates are not explicitly specialized
<source>: In function 'int main()':
<source>:21:38: error: static assertion failed: Not working
   21 |     static_assert(test_var.test<char>('a'), "Not working");
      |              

Tested via: https://godbolt.org/z/rToMEYYbc

A few things I tried were:

template<typename T1>
template<>
constexpr bool A<T1>::test<char>(char _) // <- this is not compiling
{
    return true; // imagine this is custom behavior for A<T1>::test<char>
}

template<typename T1>
constexpr bool A<T1>::test<char>(char _) // <- this is not compiling
{
    return true; // imagine this is custom behavior for A<T1>::test<char>
}

template<typename T1>
template<typename>
constexpr bool A<T1>::test<char>(char _) // <- this is not compiling
{
    return true; // imagine this is custom behavior for A<T1>::test<char>
}

template<typename T1>
template<typename T2=char>
constexpr bool A<T1>::test(T2 _)
{
    return true;
}

template<typename T1>
template<typename T2=char>
constexpr bool A<T1>::test(char _)
{
    return true;
}

template<typename T1>
template<typename T2=char>
constexpr bool A<T1>::test<T2>(T2 _)
{
    return true;
}

No success with any of those.