Pin heap span & Forward as memory

PinHeap_ForwardAsMemory.cs

unsafe class TemporaryHeapMemoryReference_MemoryManager : MemoryManager<byte>
{
    private readonly unsafe byte* _ptr;
    private readonly int _length;

    public  TemporaryHeapMemoryReference_MemoryManager(byte* ptr, int length)
    {
        _ptr = ptr;
        _length = length;
    }

    protected override void Dispose(bool disposing)
    {
    }

    public override Span<byte> GetSpan()
    {
        return new Span<byte>(_ptr, _length);
    }

    public override MemoryHandle Pin(int elementIndex = 0)
    {
        throw new NotImplementedException();
    }

    public override void Unpin()
    {
        throw new NotImplementedException();
    }
}

static unsafe void EatSpan(ReadOnlySpan<byte> span)
{

    fixed (byte* p = &MemoryMarshal.GetReference(span))
    {
        TemporaryHeapMemoryReference_MemoryManager mgr = new TemporaryHeapMemoryReference_MemoryManager(p, span.Length);
        EatMemory(mgr.Memory);
    }
}

static void EatMemory(ReadOnlyMemory<byte> memory)
{
    
}